Those are the two largest manufacturers of rubber flashlights in the world. As someone who likes rubber flashlights, I have plenty of examples from both so can share some observations:
Both use the same kind of cheap plastic clicky switch that is commonly found in cheap 6V lanterns. Both use riveted strips of copper and use the rivet heads themselves for the + battery terminal, just like you'd expect in a cheapo flashlight. They are pretty much equivalent in quality, but the Garrity costs less. Garrity has the unfortunate habit of putting patterns like a few fresnel lines on their lenses, that serve only to make the beam pattern funky. They also seem to facet only the tops of the reflectors (rather than only the bottom like Eveready) so the spot shows all the artifacts of a smooth reflector AND the spillbeam has this projected disco ball appearance. At least with an entirely faceted Dorcy you get a nice smooth spot with your disco light. The Duracells have a smooth reflector. Both have a lifetime warranty except for the Durabeam line so even Gilette knows those are junk (maybe simple press contacts work for Photon but a PR base should not be a contact for the switch...)
The original Garrity Tuff Lite had a rugged industrial appearance with sharp, square rubber blocks, and the Angle Head was ribbed. The 2nd generation from the '80s until very recently, had a melted chiclet appearance from the rounded blocks, and the new ones in stores now are very heavy and ribbed. I prefer the oldest ones because the 2nd gen had the funky lenses and the new ones are pretty heavy and clunky. The rubber Duracells are shaped like a peanut but have a small flat so can tailstand. In exchange for the ergonomics and syle they are very inefficient with space; the AA model is about the size of a 9P, for example.
But there's something to be said for a finish that looks new even after being dropped or thrown. Try that with a 9P.
And yes, this gives Gilette/Duracell access to much better LED lights than their archrival Schick Wilkinson-Sword/Energizer.