It should be exactly the same.
The only difference between a carbine and a pistol is the pistol upper has to be mated on a lower receiver designate as a pistol lower at its time of manufacture (which I think is what the poster above was trying to say.
The gas port, and everything else, should be the same between the two.
The only reason one would require an FFL would be if you’re looking at the complete unit with the lower receiver.
Or, you’re looking at an SBR setup, in which case, you need a dealer that can handle NFA firearms.
Oh, and I agree with the above, I’d stay away from Model One Sales.