Macro biotic: brown rice and miso. And seaweed. This mindset is completely foreign to me; these people are typically card-carrying PETA members in my experience.
Vegan: not necessarily ethical lines here. Just means no cheese or eggs too. I used to be one of these, but I love a good double Gloucester omelet too much.
Vegetarian: Eats cheese and eggs. Can still be one for ethical reasons.
Flexitarian: vegetarians who occasionally eat meat, or carnivores who occasionally eat vegetarian.
Trivia: 70% of the subscribers to Vegetarian Times are not vegetarians. Most people who buy things like Boca Burgers and the like are not vegetarians either. Current guesses put strict vegetarians at 3% of the population in the US.
Me, I'm a vegetarian for non-ethical reasons. I'm not terribly careful about making sure that the authentic Mexican refried beans don't have lard, and I don't mind chicken broth in the soup or the rice. And there's this really good mandarin orange and blackened chicken salad that the company caters in occasionally... bottom line, though, is that I don't eat meat 99.9% of the time.