freeway vs parkway

freeway

noun
  • A toll-free highway. 

  • A highway with grade-separated crossings (rather than level crossings) and designed (and only permitted) for high-speed motor-traffic running in two directions on one separate carriageway each 

parkway

noun
  • A scenic freeway. 

  • A tree lawn. 

  • A divided highway with a landscaped median. 

  • a railway station built on the edge of a town, typically with a large car park to function as a park and ride interchange. 

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