How do you know your best friend likes you that way?

So, like, what are the differences between treating someone like a best friend and treating someone like a potential mate. I mean, say, the girl in question has en enlarged personal bubble, so not a lot of really touching and everything. I'm talking about amount of talking, when she talks to you, how she acts when you're around her, how she flirts (like teasing like a little kid teasing if that's flirting in any sense) etc. My best friend says she doesn't like me but I have a very different idea because of how she acts. I just need to have a general guideline, not a critique of what I've said so far.