Orgasm?

So I've only recently begun exploring my body with my current boyfriend (before him I had never even kissed a boy before) and I'm really loving some of the things we're doing and that he's doing to me, but he sometimes asks afterwards if I came and I don't actually know? 
I know orgasming is supposed to feel amazing but I don't know if what I'm already feeling (which is great) but is there a difference between actually "cumming" and just getting sexual pleasure from it? Thanks xx