Is it cum or pee?

I been looking this question up for days.. I couldn't find a correct answer.. but like when you about to cum do you like feel like your going to pee? is it like the same as pee sensation? because whenever I be having sex, I always get it.. but I be holding it in. And my boyfriend always asking me why don't I ever cum.. and I told him I be feeling like pee sensation and he says that's probably cum.. but I don't know.. I don't wanna pee on myself.. and when you do cum, does it just come out itself, or do you have to push out? I'm just so carious..