What is the great difference between these two schools? The Theravada is very strict. It is a way for monks, essentially, rather than laymen. There are many ways of living Buddhism. The Theravada Buddhists are trying to live without desires: to have no need for wives or girlfriends, husbands or boyfriends; not to kill anything at all; living in the strictest vegetarian way; and even straining their water so that they do not eat any little insects with it. Also in this very strict way, they meditate all the time and eventually attain nirvana, which involves total disappearance from the manifested word.
This branch of Buddhism is associated with Southern Asia, including Thailand and Cambodia. Which shows you how much it isn't practiced by laypeople, at least if restaurateurs are any guide. Seriously, a Thai restaurant in almost certainly not a vegan restaurant.
But the Buddhist religion interests me. Not necessarily as a practitioner or adherent, but certainly as an admirer. More than any other major world religion it seems to be a way of thinking rather than a set of beliefs.