I practice Vegansim which rejects the commodity of animal products.
That is funny, because I am also a vegan.  Are you a dietary vegan?
Yes, I am a dietary vegan.  I refrain from consuming all animal products.
Are there a lot of vegans in the United States, or are there more vegans around the world?
Not sure about the numbers in the US but India has strong cultural and religious traditions that promotes vegetarianism which can be applied to being vegan.
I have a lot of friends that say they are vegetarians, how is vegetarian different from vegan?
Well there are variations of the diet.  There aer some who eat eggs and dairy products, but still no meat.