The biggest difference between a playback system and a music reinforcement system:-
A music reinforcement system that encompasses a wide frequency response bandwidth, and is capable of high instantaneous sound pressure levels.
A playback system doesn't include microphones; it simply plays prerecorded material. may be a system that's used for inter-communication between people or rooms.
A sound reinforcement system is that the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that produces live or pre-recorded sounds louder and will also distribute those sounds to a bigger or more distant audience.
Music systems are often Bluetooth enabled and function a speaker for mobile devices. they will also hook up with satellite units for multi-room playback.