flagstone vs paver

flagstone

noun
  • A flat, rectangular piece of rock or stone used for paving or roofing. 

  • One of several types of rock easily split and suitable for making flagstones. 

paver

noun
  • A flat stone used to pave a pathway, such as a walkway to one's home. 

  • One who paves; one who lays pavement. 

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