Hi there! I have been in an opposite possition as you are in, so I think I can give you some good insight
I started ASMing and PSMing community theatre before I was involved in my college productions. While thus far at college I have only ran a sound board, I have witnessed key differences.
A major, major difference I noticed was the role of the director. Community theatre seems to be a good middle ground between academic theatre and something a tad more professional than community. You will have more responsibility and not have someone looming over you as much in academic theatre and the actors have a different mentality.
In academic theatre it stood out to me that the director just stuck around and was involved TOO much and as a result, the SM didn't have much control in academic theatre. If there was a problem everyone went to the director because they were the professor and the SM was just a student.
Community theatre though will have people there willing to help you, namely the producers. If you are nervous, tell them and they can be your best friends. Community theatre is people doing theatre for fun more-so than for learning or for a job. And while we all have fun doing theatre, there is a unique vibe I have found to community. I really found myself and my style as a PSM at community theatre. Plus, having a base that you already have, you will do fine. Enjoy