Vegetarianism/veganism ranges quite a lot between people. The mildest vegetarians simply don't eat meat if there's a vegetarian choice, but don't worry too much if they have to eat a bit of meat because there's nothing else. They might also have no problems in eg. eating fish. They usually don't have any problems in eating animal products that aren't meat (such as milk products and eggs.)
Vegans, unlike vegetarians, do not eat any animal products (not even milk products.) The most open-minded vegans, however, do likewise not worry too much if there's a situation where there's no choice than to eat some animal products (or even outright meat.) They do not adhere to veganism religiously, they simply follow it given the choice, but do not stress too much about it otherwise.
The type of vegan that really amazes me, though, is the obsessive vegan. Not only do they avoid all kinds of animal products religiously, they are in fact pathologically obsessive about it. They treat animal products like a person who has an extreme form of peanut allergy treats peanuts. Even a single molecule that has come from an animal is too much!
I'm not exaggerating a bit here. For example, I was once queueing at a Subway, and before me there was this kind of hippie-looking young man with dreadlocks and clothes that look like they are made of burlap sack material. (He even had a bag that was made of the same material.) I think you know the type. Because it was a quite busy hour of the day, the Subway employee was dealing with two clients at a time (ie. making two breads at the same time.)
When the hippie before me, and the person before him, got their turn, the latter asked for some bread containing sausages and the hippie asked (unsurprisingly) for the vegetarian break. The employee asked him if he minded if she made the two breads at the same time, as the other bread would contain sausages. The hippie refused. Those sterile gloves were not going to touch the sausages and his vegetarian bread. The employee had to make the breads one at a time (and change gloves in-between, of course), delaying the entire queue.
I don't understand what exactly is it that this hippie is trying to achieve with this. The whole situation felt like he thought of the whole meat thing as a religious profanity, and if even a single molecule of meat entered his mouth, he would be unclean and sacrilegious.
Such vegans only make their lives (and sometimes other people's lives) a lot more difficult than it has to be. They have to watch everything they eat, like if they were extremely allergic. And for what? What good does it do to anybody?