nursery rhyme vs poem

nursery rhyme

noun
  • A short poem or song for children, mostly anonymous or handed down by folklore 

poem

noun
  • A piece of writing in the tradition of poetry, an instance of poetry. 

  • A piece of poetic writing, that is with an intensity or depth of expression or inspiration greater than is usual in prose. 

  • A literary piece written in verse. 

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