I don't really see a difference. I guess people use gorgeous when they're tired of beautiful
To me, I feel it's in the moment. Beautiful seems to be a lesser word for gorgeous, as if it were better. To me they are just words. I love getting called those words, it does make me feel pleased/flattered, sometimes blush. But the moment is what really implies the words. It could be either loving, sexy, or both:)
Beautiful christina aguilera
Gorgeous Brittney Spears
Gorgeous: A way of telling a girl she looks good (facial appearance, well dressed, etc) usually a way of telling a girl she's more than pretty or cute.
Beautiful: Used to describe all attributes of a girl like personalty along with looks. Usually used when commenting on someone a guy likes. Ex: If a guy calls some one beautiful when she's wearing sweatpants with her hair tied up with no make up on it usually that's he's think she's wonderful on the inside out.
P.S. I would call someone I didn't like gorgeous, but if they were my girlfriend Id probably call them beautiful.