I was looking at the Futaba 7 channel radio and saw several different model #'s. It seemed there were two different sets of servos for 2 of them but what is the difference in them all?

7caf
7cap
7chf
7chp

I belive all that end in a p are pcm's. Correct?

Thanks.

correct, and a is aircraft, h is heli. (they really basically are the same, read up here on the differences between the two)