playgroup vs preschool

playgroup

noun
  • An informal organised group providing care and activities for preschool children. 

  • A group of children who meet together for supervised play. 

  • A group of gamers who meet together, especially for role-playing games. 

preschool

noun
  • A nursery school. 

verb
  • To provide nursery school education for. 

  • To undergo nursery school education. 

adj
  • Of or relating to the years of early childhood before attendance at primary school. 

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