Hi!
A good resource for this kind of question is TekWiki.
You can download instruction & servicemanuals for your scopes here:
There are also Tektronix catalogs available for download:
Your scopes were introduced in the 1982 catalog.
To sum it up: the 2215 has a second timebase which gives some more possibilities for the horizontal modes. The possibility of interchanging parts might depend on the serial numbers of your scopes.
Holger
