The only difference is that Thompson Center stopped putting the overtravel screws on the very newest frames. I just drilled and tapped my frames, went to the hardware store and bought a #6 set screw and did it myself.
What most barrel manufacturers are doing now is boring the 22LR and 22 Mag a little "off center" so that you do not need a switch on the hammer. The regular firing pin just hits the rim fire cartridge on the edge. Works really well!
As far as getting rid of one or the other, why?

It has been mentioned to you about the legal issues around switching barrels from pistol to rifle and back again. The parts will interchange easily enough though. For sure don't put a pistol barrel on a frame with a rifle stock, that will get you busted in a hurry!
It's a dumb law and there's a good chance that you'd never get caught, but.......I have one of each just in case.