firewood vs kindling

firewood

noun
  • Wood intended to be burned, typically for heat. 

kindling

noun
  • Small pieces of wood and twigs used to start a fire. 

  • The act by which something is kindled. 

adj
  • Illuminated, lit. 

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