A dedicated 20 Amp circuit consists of:
a] a 20 Amp circuit breaker
b] All in-wall wires rated at 20 Amps or more (12AWG)
c] All in-wall wires only going to the specified 'dedicated' outlets
d] Receptacle's may be 15 Amp (2 or more) and/or 20 amp
The only real difference between a 15 Amp receptacle and a 20 Amp receptacle, is that you can insert a 20 Amp plug into the 20 Amp unit. All the internal parts of both receptacle's are rated at 20 Amps