Not sure if regular MK4 and Jubilee MK4 are the same, regular MK4s have the same graphics capability as the older MK2.5 games whereas Jubilee MK4s seem to have better graphics, almost on par with MK5 (still low-res though)... That said, the boards I've seen pics of tend to have blanked EPROM sockets (they were never populated from the factory) so there were probably different board revisions.
Normal MK4s have just 10 game chips (2 program ROMs, 6 graphics ROMs, u59 video/sound chip, u71 color PROM), Jubilees have a lot more.