In the community, they often talk about attraction as if physical attraction and sexual attraction are the same. "Oh, she's hot, we have to want to fuck her".
In real life, it doesn't work like that. Indeed, scientists have classified attraction into 6 categories.
There's 1) physical attraction, 2) sexual attraction, 3) social attraction, 4) relational attraction, 5) task attraction, and 6) fatal attraction.
1) Physical - needs no explaining, but I'll do it anyway. We're drawn to someone because of the way they look. It's why girls can say another girl has nice boobs and still not want to suck on them.
2) Sexual - we want to fuck someone because they get us aroused. Why do they get us aroused? Any number of reasons, not always physical. She could just be massaging our glans while we ponder this question.
3) Social - hey, he or she is fun to be around and talk to, so we're drawn to them. Do not confuse for sexual attraction. This is why girls will hang around guys they have no intention of fucking - the guys are fun to be around.
4) Relational - when we think someone will make a good girlfriend or wife rather than "I just want to tear that pussy up".
5) Task - think back to middle school when you had to pick teams for basketball. Your first pick...you didn't want to fuck him? No. You just wanted to have a winning team. Same deal, you're drawn to whomever you feel will help you get the job done best.
6) Fatal - You know when you start hating the very thing that first attracted you to someone? Like that you guys argued about everything on your first date? But then you loved it and now you want to put a bullet in either yours or her head? Yeah, that's fatal attraction.
Neither exists in a vacuum. But it's important to note that if you're aiming for sexual attraction, it's pointless to go about it through non-direct means.
That is to say, if you want to get into her pants, do not consciously try to be her friend or do her homework.