sidewalk vs walkway

sidewalk

noun
  • (usually) a paved footpath located at the side of a road, for the use of pedestrians 

  • any paved footpath, even if not located at the side of a road 

walkway

noun
  • A clearly defined path for pedestrians. 

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