In my mind, there are two types of vegetarians, those who do it on principle and those who don't like meat. I fall into the second category, having loathed red meats since being a very small child although I would eat chicken, sausage and a small amount of fish under sufference.
However, when I was in my early twenties, I attended a party at a vegetarian friend's house and whilst eating veggie burgers, commented that it was nice to eat without feeling guilty. The friend suggested that perhaps I was bordering on vegetarian and I realised he was right and happily denounced all meat there and then. Of course this then opened up a huge can of worms with regard to how far to take this thing. I went the whole hog, no eggs or fish, only ate vegetarian cheese and turned my back on leather products although the shoe principle was fairly shortlived from a practical point of view if nothing else.
As with the majority of lapsed vegetarians, bacon was my downfall and many years later, after marrying an avid carnivore, I succumbed to temptation and started eating a small amount of meat again. I am now back to where I was before that fateful party, eating meat occasionally more due to an awareness that my diet was probably inadequate before than a longing for meat. I have now have a daughter who is just as committed a carnivore as her father so have to cook red meat on a regular basis which is not something I relish and still will not eat but as a parent, I just get on with it.
I think it is all down to each person's individual level of comfort with what they are eating as to how far they take it. I would suspect the majority of people who give up meat as a matter of principle are more likely to become vegans because it is very difficult to decide where to draw the line once you have looked into it thoroughly.
I do not consider myself to be a vegetarian but will often order the vegetarian option at a meal out or party because it is easier to try to tell people that than try to describe to them what you will and won't eat and be considered to be just awkward.
Just my take on things anyway although I'm sure some people will disagree.
D x