Supertwin II pups/ supertwin 750 pups: which différence??

Hello!
I just purchased a rainbow 2 (1983 version 1) , I already had a very nice and good rainbow 1 (1983 version 3) and i am surprised that the R2 sounds better than the R1.
The sound is thicker and more precise.
Even tough both guitars have very similar specs (exept the fretboards and the deco) I noticed that the R1 have Supertwin II pickups while the R2 have Supertwin 750.
Are these pickups really differents? May this difference explain the obvious difference of sounds?
Thanks.

Take 'em out and see what's printed on the underside! I'm prepared to bet that Supertwin 750 equates to MMK75.

Thank you Corsair, It 'd probably be the best to do, but as long as i'm not handy at all, i dare not touch those guitars by myself (exept for playing), so I have to wait untill the luthier makes it.
And more, even if you were right about betting that Supertwin 750 = MMK75, we could be sure only if we found MMK75 printed on the pickups of my Rainbow 2.
..And what about the supertwin II ?