railcar vs railway wagon

railcar

noun
  • Any unpowered railway vehicle 

  • A self-propelled railway vehicle for passengers, similar to a bus. 

  • A powered single railway vehicle designed for passenger transport, with a driver's cab in both ends; Not to be confused with motor coach/motorcar, which is a powered railway vehicle capable to haul a train. 

railway wagon

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