What's the difference between "insure" and "ensure"?

Insure is to secure or protect something such as a belonging like a car or house by taking measures to do so (sorry, I know I am pointing out the obvious here)

Ex: I need to insure my house, in case anything were to happen to it.

Ensure is to to make sure or certain of something.

Ex: To ensure that your transaction has gone through, you must provide proof of identification.

(I added examples for further clarity)

The 2nd one is liquid food and if you want to INSURE that you live a full life you're going to want to drink some ENSURE.

Insurance companies rip you off. Ensure is a drink for the weak.

The verbs assure, ensure, and insure all have the general meaning "to make sure," and even though some argue that they are interchangeable (1,2), many maintain that their usage is dependent on context (3,4,5,6):

Assure is something you do to a person, a group of people, or an animal to remove doubt or anxiety, as in Squiggly assured Aardvark that he'd come to the party early. You can remember that assure can only be used with things that are alive (and both assure and alive start with a). Only things that are alive can feel doubt or anxiety, so only they can be assured.

Ensure is something you do to guarantee an event or condition, as in To ensure there'd be enough food, Aardvark ordered twice as much food as last year. You can remember that guarantee has those two e's on the end to help you remember that to ensure (with an e) is to guarantee something.

Insure can be done to a person, place, or thing, but it's reserved for limiting financial liability, most commonly by obtaining an insurance policy, as in Aardvark wondered if the caterers were insured against loss. You can remember that we take out insurance to protect our income if we become unemployed, disabled, or injured in an accident. Both insure and income begin with -in.

Finally, the related verb secure is used when you take possession of a thing or place, as in Aardvark secured a beautiful hall for his party, or when you make something stable or safe, as in Aardvark secured the welcome banner to the wall.
Quick and Dirty "Ensure," "Assure," Insure" Tip

So the quick and dirty tip is to use assure for things that are alive (remember that a is for alive), ensure to guarantee events and conditions (remember those two e's at the end of guarantee), secure for things and places, and insure for all of the above in financial contexts (remember the i is for income).