I don't know if this guy I'm talking to really likes me or is just sexually attracted to me?

Well... If he spends most of his time pressuring you for sexual favors, that's a sign. If not, that's also a sign. If you're careful not to let the guy take advantage of you, it will be easy to see whether it's love or lust.

All guys are sexually attracted to most girls. its animalistic. but whether he wants to be with you in a relationship is something that varies from man to man. but some signs are
1. does he know those ( little things ) about you. eg fav color, food, candy, your birthday
2. does he let you have his things. typically a guy won't let a girl have his stuff if he knows he's not gonna see her too often. does he let you use his ipod, borrow clothing, cd's, movies. these things say I trust you, and I plan on seeing you again soon
3. does he want to meet your family. does he mind spending time with you in front of your parents. this would say he wants to earn their respect because he's gonna be around for a while.
4. does he skip things he likes doing to be with you. I personally liked a girl once, and I love boxing, I was missing training sessions because this girl would call ( we were engaged, we have a little boy now but our relationship ended after 5 years. )

there are a million and one signals.

DO NOT HAVE SEX WITH HIM FAST IF YOU WANT TO KEEP HIM. men are hunters, we need the chase. and we say we don't think it, but when a guy waits for it, we feel that anybody else probably had to wait too, and you won't easily let the next guy in. we whine, and complain and moan about her not giving it up, but in the end we respect it, and appreciate it. its one of those LOVE TO HATE IT deals.