Huge differences, 1) Afghans and Vietnamese were fighting for their homelands, 2) They knew the terrain, the Americans didn't, 3) The terrain in Afghanistan and Vietnam supported asymmetrical warfare, 4) The Afghans especially had a history of armed fighting, even the civilians, 5) The Afghans and Vietnamese had the support of the local population and could hide when needed among civilians, something the Jews could not do
Therefore you argument that the Jews with guns could have faced off the German army without most of them being killed is flawed as only a gun loving American could put forward.