Going from version C to A or B, anything I should know?

I've only played version C, but I might enter a tourney at the arcade that is only a version A or B. I play Lion, and my brother plays Jacky and Vanessa. Is there any major differences I'll notice that might hurt me since I've never played these versions? Are the moves done the same, or are the combos the same?

I just don't want to enter, and get my ass kicked all because the version is so much more different and I find out my moves or combos won't come out cause they changed them.

Any help is appreciated.