Need help understanding weapons

I’ve been playing Fortnite for a bit now and I’m generally in the top 3-6 per game, but I’m having trouble with weapons. I do best with the Rapid Fire SMG, the surgical burst rifle, etc. Can someone please help me understand the different kinds of weapons and when you would want to use one over another? I read online that there’s ones good for shooting far away but I’m finding I struggle more with these.