[97BladeRider]

In 88, the ZX6 was the race-replica, while the 600R was a geared down street bike version.

Almost like the difference between a Suzuki GSX-R and a Katana.

EDIT:

Actually the first year of the ZX-6 was 1990, so anyone calling a 1988 Ninja 600R a ZX-6 is mislabeling it. But what I said above still stands about the 1990.