fir vs pinus

fir

noun
  • Any pinaceous conifer of related genera, especially a Douglas fir (Pseudotsuga) or a Scots pine (Pinus sylvestris). 

  • A conifer of the genus Abies. 

  • Wood of such trees. 

pinus

noun
  • Any member of the genus Pinus; a pine. 

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