BJJ,Submission,Grappling

I was hoping to get some advice.

Currently I'm taking BJJ, one of the clubs I goto is avid about students doing competitions.

So, I've been entered into a no Gi submission tourney a month from now. Can someone tell me how a submission tourney is different from BJJ?

How does Grappling and Catch comps fit into the scheme of things also would be helpful.