yeah. cause i think sexy here in the us is skinny, big breasted, wears revealing clothing, really long hair, really big lips, really big eyes, looks stupid. they're not into intellect as being sexy
I think that reflects more of a stereotype of what many women think men think sexy is, perpetuated by the entertainment and fashion industries. Your average US male will find a large variety of women to be "sexy" to them. And many of us absolutely find "intellect" to be sexy.
I guess fundamentally "being sexy" is an attitude projecting sexual availability and desirability... a lot of that is culturally based, but universally around the world if a woman or a man wants to be "sexy" they prepare themselves in whatever way it means in their culture to show "sexual availability." In the US that usually means dressing in certain clothing, makeup for women, nicely prepared hair, and a certain attitude.
People can be "sexy" just by a shift in attitude towards another however, although a disheveled unwashed person is unlikely to be sexy to anyone lol.
Your original question is a bit more difficult however. I tend to think of "sexy" as attitude, so to me your original OP is more about "beautiful" or "Handsome" vs "Cute". In general I think if someone has more "childlike" appearance, such as rounded features, big eyes, small nose, etc, then they are more likely to end up with the "cute" label. Someone that has more classically adult features that match cultural beauty ideas is more likely to be called "beautiful" instead of "cute".
Anyone can put out a "sexy" vibe though, even if they arn't considered either traditionally "cute" or "beautiful" by a particular societies standards.
</random musings>