football pitch vs playing field

football pitch

noun
  • A playing field on which the game of football is played. 

  • An informal unit of measure of area, equal to the area of an Association football pitch (typically 76,900 square feet or 1.76 acres). 

playing field

noun
  • A field on which a game, especially a ball game, is played. 

  • Any place or context within which competitive activity takes place, such as market competition between companies. 

How often have the words football pitch and playing field occurred in a corpus of books? (source: Google Ngram Viewer )