play back vs replay

play back

verb
  • To replay a recording. 

replay

verb
  • To display a recording of a previous event, especially multiple times. 

  • To play again. 

noun
  • A repetition of another event, scene, or occurrence; a recurrence or reenactment. 

  • A repeat or subsequent playing of some or all of something which was previously broadcast or performed, or a playing of something which was recorded, such as a live event or a television broadcast, the gameplay of a computer game, etc. 

  • A replayed match, often after the first game or match ended in a draw; a rematch. 

  • A (video or audio) recording of an action or event that is or can be replayed after being recorded; saved video footage (which is, or can be, replayed) of the gameplay of a computer game, a (portion of a) televised sports match, etc. 

  • An act or instance of replaying (of playing something, such as a game, again); a replaying of (something). 

How often have the words play back and replay occurred in a corpus of books? (source: Google Ngram Viewer )