The civil variant has sideways opening, bulbuous doors while the military opted for a wedgetail affair that allowed air-dropping.
plus of course, the obvious difference, that the civil Agosy had doors at both ends. I wonder why the RAF didn't want that option.
I remember a wonderful (Punch?) cartoon, that I haven't been able to find, that showed an Argosy being loaded by a fork-lift at the nose, with pallets falling out of the rear. The driver was saying to his mate "It's amazing how much you can load into these things!"