passenger ship vs yacht

passenger ship

noun
  • A ship whose primary function is to carry passengers. 

yacht

noun
  • A slick and light ship for making pleasure trips or racing on water, having sails but often motor-powered. At times used as a residence offshore on a dock. 

  • Any vessel used for private, noncommercial purposes. 

verb
  • To sail, voyage, or race in a yacht. 

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