The human body: does it have two types of sweat? one a nervous sweat? the other a cooling sweat? why does one cause body odor and the other does not?

Fresh sweat has no odor, but it provides a warm, moist environment in which bacteria and other skin flora thrive and multiply rapidly. It's the microorganisms on the skin that cause the odor, sweat only provides a nice environment for them.

yes we have two types:
eccrine glands
apocrine glands

Eccrine we have all threw life and cover all our body, they area heavier in the forehead, palms, and soles of the feet.

Apocrine glans we get at puberty and are in the armpits and pubic region.

Sweat doesn't smell, when it mixes with bacteria on the skin's surface, it can cause body odor. Sweating in an area that has more bacteria like your feet, armpits and pubic area will more likely cause a smell.

The reasons we sweat are fever, physical activity, and heat. All of these increase your heart rate and cause you to sweat. Just like when you are excited or nervous.

Just a note:
Deodorants do not reduce sweat but only mask the odor with fragrance.
To avoid odor because of sweat, the best method is to keep skin dry. Good hygiene will not allow bacteria to develop and multiply. Change of clothes after sweating is another method, because clothes carry sweat and can cause odor.

Also note:
Not sweating enough is dangerous and can be life threatening, sweat is the body's natural defense to maintain the body temperature. With out it you can suffer from things like heat stroke. At the same time, if you always sweat watch out for diseases that can also cause sweating. If your just not sure, ask a doctor.

Yeah, get some antipersperant (don't know if that's spelled right, don't have spell check with me) deodorant.

*Edit: Sorry, read the question wrong. I actually don't know why.