Well, MVS is Jamma +, it has all the Jamma connections plus a 4th button, and select button and stereo in some units.
You might have to re-wire the speakers to play jamma in a MVS cab, it depends on the game.
to play MVS in a jamma cab, you need to add the items mentioned above to have full support, some games dont need a 4th button, a 1-slot doesnt need a select button, and some motherboards dont need stereo. go to hardMvs.com to see a comparison chart