Hey there!
As far as I know, the 220 was introduced in 97. It shares the same bottom end as the 95+ kdx200. KDX's from 89-94 are E series, no 220 available in this time. You'll need to find out for sure what years the engines you are getting are, and then go from there.
I have seen a couple references lately to early 90's KDX220's, so I hope I am not steering you wrong. I have always been under the impression that the KDX220 was not released until 1997 though. Check out the KDX timeline on the justkdx homepage for some more info.
As far as major differences, displacement is the only huge thing. The 220 has some torque over the 200, and of course the 200 has better top end rev.
J.