In order to appreciate rear/back surrounds your seat should be several feet away from the back wall where the rear/back surrounds are mounted.
Yes, the specific name is surround speakers (those that are to your left/right basically), and as they get more info than the rear/back surrounds, I'd use better speakers in the surround position than in the rear/back surround positions....ideally you want the same speaker in every position but that's often not practical...