I'd imagine you'd get a similar situation to the ipads where the X chip is far superior in the same gen eg:
iMac - m2 chip + max out at 64 gig ram
iMac Pro - m2x chip + max out at 256 gig ram
iMac - m2 chip + max out at 64 gig ram
iMac Pro - m2x chip + max out at 256 gig ram