To me- let me put it this way. When I met my ex I thought she was pretty. VEry very pretty. After I got to know her and got to see what kind of person she was, she became the most beautiful person in the world to me. Even though we're not together anymore, I have yet to find someone who has half of what she had, and women who are generally physically more attractive then her, still seem to pale in comparison because they're not as good a person.
You can be pretty without being beautiful. You cannot be beautiful without being pretty. Beauty implies more of an "aura" than simply the physical traits. It's in the way a girl carries herself, presents herself and goes about life.
I don't think there is a definition, but here's mine. Pretty to me is someone who is just naturally good looking. There are plenty of pretty people. Being beautiful means you have it all - looks, brains, sense of humor, sweet, caring ... overall just beautiful.
I have had girls I knew in the past say a girl was pretty/attractive/ etc then I saw her and I was like huh what. I have found it seems to be all or most girls seem to think ALL girls are pretty/attractive/ etc.
Then again look are by no means everything they only play a tiny part of who there person is personality has to count huge and actually be there in the person, no one is going to get by on their looks.
Beauty is only skin deep. I consider pretty as someone being physically appealing. Blatently their personality sucks or has not shown through yet. Such as the quote says. A beautiful person is someone who has the heart, brains, and personality that coincide with being physically attractive.
I think beautiful is a stronger word than pretty - many people are pretty, few are really beautiful. Doesn't have anything to do with personality, but does incorporate how someone presents and carries themselves, if that makes sense.