billiards vs pocket billiards

billiards

noun
  • A two-player cue sport played with two cue balls and one red ball, on a snooker sized table. 

  • Any of various games played on a tabletop, usually with several balls, one or more of which is hit by a cue. 

pocket billiards

noun
  • Any of a family of billiards games played on a specific class of billiards table, having six receptacles called pockets along the rails, in which balls are deposited as the main goal of play. 

  • Synonym of pocket pool 

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