That's a big question - especially with no context to refer to. There are a lot of good grammar books which provide examples; it could be an idea to invest in one!
Essentially though the difference is the same as the difference between simple and continous if you take away 'may' and rephrase the sentence as:
I will possibly work.
I will possibly be working.
Maybe I'll work.
Maybe I'll be working.
So the 'be working' just adds the 'continous' idea of an action in progress at a moment in time.