Aside from the one champion that shows up, they are mechanically the exact same, just all the enemies have more hp and hit harder. Everything is just so tanky that it's not fun to fight. We run out of ammo constantly, so it ends up often just a tedious, slow burn on the boss between phases with little to no actual difficulty. It's like, normal ones are super easy, but then we have the Legend ones that just feel like a slog. They aren't fun. On a side note, I also still dislike the fact you actually have to tag a headless one to get credit. So if you have competent allies in a normal run who can burn it down quick, you might just not get credit.