I do not quite understand how this works. My Meta user here has 509 rep, and my main user has 513 rep. Why is there that difference? It would seem to me that, since I have not answered/asked any upvoted answers/questions, that I should have 101 rep. Or, if Meta.SU is a "sub-Q&A" of SU, then I should have 513 rep here. I would like someone to explain to me how rep carries over from SU to Meta.SU.
Your MSU reputation is updated regularly (once an hour or so) from SU. In the mean time, the values can be slightly different due to caching.