What's the difference between an engine and a motor?

The basic difference is what they use to produce mechanical work.

General rule of thumb is that Engines use thermal energy of some form (steam, petrochemical combustion) while Motors convert electrical energy into mechanical work.

I don't want to sound adversarial but this has been a pet-peave of mine for nearly 30 years. It is not a matter of opinion but is truly scientific terminology. The 2 devices are only similar in that they produce "Mechanical Work".

The word Engine is taken from the term "Heat Engine" which is used to describe a device that converts Thermo Chemical Energy or Heat Energy into Mechanical Work. Hence you can say that Jet Turbines, Steam Power and Internal Combustion devices are in fact "Engines".

Whereas...

The word "Motor" was shortened from the original term "Electric Motor" which is used to describe devices that convert "Electrical Energy" into "Mechanical Work". Hence you can say that Drills, Winches, Saws and some newer Electric Cars have "Motors".

But most Engines rely heavily on motors, as just one example the 1970 Hemi Cuda may have a Hemi Engine, but that engine has an electric motor as its "starter" without which it cannot be started.

If you look at definitions, there is actually no difference. However, most people associate an engine with something that produces power within, while a motor is something that requires outside energy such as electricity.

Engine:

a machine that converts fuel or gas into mechanical power or motion

Motor:

A machine that converts other forms of energy into mechanical energy and so imparts motion.

I believe that an engine requires no outside source of power to run. An motor does.

In terms of etymology, originally motor was just another word for mover, especial "the prime mover", i.e., the thing that moves the rest of the device. Meanwhile, originally, an engine was any device or system (mechanical, chemical, electrical, or even human, social, or political) that effects a result: a catapult is an engine, a crane is an engine, a bomb is an engine, a political party is an engine, a water-powered mill is an engine, a criminal gang is an engine, and a man with a singleness of purpose is an engine. Gradually through the 19th century "engine" became especially (but not exclusively) associated with fire, boilers, furnaces, and bombs -- in short any device that tended to get very hot and explode, but the whole system was still considered "the engine", not just the prime mover (the motor). In the 20th Century, Americans took to calling a car motor "the engine", even though the suspension system, steering system, braking system, gearing, and whole drive train are really collectvely "the engine".

Also, re. t3h_Jakal, the word Engine is NOT taken "from the word Heat Engine [sic]". It comes from the Latin word INGENIUM (from which we also get "ingenious") and prior to the 1800s just meant any contrivance that acheives an intended result. It can be and is still used this way by those with a literary bent with a gift for words. And "Motor" did not originate with "Electric Motor": there were motors long before that: motors powered by wound springs. The fact that Faraday felt obliged to put the qualifying adjective "Electrical" in front of "Motor" implies he did so to distinguish it from the common motors of his day. The same is true for Watt's placement of the term "Steam" in front of "Engine" to qualify what kind of engine it was, and to thus distinguish it from the typical engines of his day.

Can't remember where I read it, but, always understood that the engine releases energy and the motor converts energy. Anything deriving energy by combustion (gas engine, coal-fired steam, ...) would be an engine and would be environmentally unfriendly. An electric motor powered by hydro-electricity, wind-power, solar power (all natural sources of energy) simply converts natural energy to electric energy and back to mechanical energy/force ... environmentally friendly. Time we converted from an engine driven to a motor driven economy/society?

an engine produces it's own power
a motor requires power from an outside source.

nuff said.

re: t3h_JaKaL

I understand you were focusing exclusively on the technical meanings, and I'm sorry if my post was less than charitable in tone. I really just wanted to point out that the words had - and still have - non-technical meanings which predate the technical ones, and from which the technical ones derive.

re: Jack Wallace
I was speaking in relation to the standardized conventions of the science of mechanics in relation to the the actual question being asked. I didn't realize he was asking for the root origins of the words themselves. I do see what your saying, but thats going a bit beyond the spirit of the question. So sure we can go into the latin meanings of words or we can try to answer the question in a format that fits the actual question. So basically since my first name is Donovan people ask where my name was taken from, and so I tell them my mom was a child of the 60's and that I was named after some singer from that era, but instead of answering them in a way I knew they were asking I instead say that the name Donovan means "From an Irish surname which was derived from Ó Donnabhain meaning "descendent of Donndubhán". The first name Donndubhán is composed of the Gaelic element donn "brown" combined with dubh "dark" and a diminutive suffix". But in reality they were asking for the first answer. See what I mean? Seriously I am not trying to argue, just reason with you on why my answer is what it is and I still stand by it.

I noticed there was a difference while driving a hybrid Prius rental. The diagram showed both... The motor was electric, while the engine was combustion based. In most cars, the two are probably combined. In a hybrid, they are separate. The engine burns fuel. The motor runs the car.

Only one correct answer in the bunch. Mubashir. Sorry folks...the energy source has nothing to do with it.

Motor is from latin Moto (Suo Moto) meaning motion. It is the device responsible for the source motion..in most cases I can think of it is the initial torque..the turning of the crankshaft.

Engine is about natural capacity, always modified by an adjective..fire engine, racing engine, boat engine, business engine....no such thing (literally) as an engine all by itself. It has to be doing something if used correctly.

The motor is the part that provides initial motion (On a big twin Harley it is the jugs and the crankshaft) regardless of the source of energy (gas, electric, etc). The engine adds the transmission and driveline to make a machine for productive purpose (motorcycling, racing, boating, business.)

Engine is usualy indicative of internal combustion while motor is(but not always) usually indicative of electric.

Re: Re: Jack Wallace

No worries, It is still kinda cool to know the root to commonly used words we take for granted every day. Sometimes commonly used words have downright offensive origins, or words we considered "bad words" and ground our children for using, are used in ordinary speech in other cultures. I think its fascinating where some words come from and how their meaning has become quite different in modern definition that the original usage.

So definitely no hard feelings. :)

In my opinion, both are energy generators difference being an engine has the ability to generates mutliple levels of power from low torque to high torque via different input levels while a motor generates a constant power, non-adjustable regardless of input.

In engine the reciprocating motion of piston is converted into the rotary motion but in motor electrical energy rotate the motor shaft.

A MOTOR IS A DEVICE THAN CONVERTS ENERGY INTO MOTION...IT CAN BE AN ELECTRIC MOTOR AND A GASOLINE MOTOR.

Can't remember where I read it, but, always understood that the engine releases energy and the motor converts energy. Anything deriving energy by combustion (gas engine, coal-fired steam, ...) would be an engine and would be environmentally unfriendly. An electric motor powered by hydro-electricity, wind-power, solar power (all natural sources of energy) simply converts natural energy to electric energy and back to mechanical energy/force ... environmentally friendly. Time we converted from an engine driven to a motor driven economy/society?

engine:

Even though both carry simularities in the dictionary. A personal though comes to mind that the term motor is used as a verb. "look at him motor!" This terminology would reflect that motor may actually be derived from this verb usage into a noun becuase of how it was adapted by companies in the auto industry.
The engine is a noun and a product that is produced by compaines that use the term motor in their name.
General Motors and Ford Motor Company....
When you look into this more closely, the companies are actually using motors as a verb to describe their activity of producing engines! It is quite possible that motor became a slang or loose term of the engine from this expanding its use in the english language.

The difference is that a motor creates work from and outside source that does not rely on a supplied fuel and oxidizer (like air). Examples are electric motors and solid propellant rocket motors which contain their own fuel and oxidizer.
Engines do require supplied fuels and oxidizers. Examples are automobile engines, steam engines, and liquid rocket motors.

engine:
Any thing which convert energy into work is called an engine.
Motor:
A part of engine drive the engine or drive by the engine or a device produce rotary motion
used to convert energy only into mechanical work.
Differance:
it seems that both convert energy into work but when we say engine it means we talk about the whole system while motor is the part of that system.


please send me reply.......

i was just thinking about this the other day. motor=elctric (weedwacker, remote control car, etc), engine=gas (car, truck, etc). then why do they call boat prepution, "motors"? a boat "motor" runs on fuel, not electricity. and what is the purpose of a "motor-home" when it's an engine in the vehicle. shouldnt it be an engine-home?