preface vs preliminary

preface

noun
  • An introduction, or series of preliminary remarks. 

  • A title or epithet. 

  • The beginning or introductory portion that comes before the main text of a document or book. 

  • The prelude or introduction to the canon of the Mass. 

verb
  • To give a preface to. 

  • To introduce or make a comment before (the main point). 

preliminary

noun
  • A preparation for a main matter; an introduction. 

  • Any of a series of sports events that determine the finalists 

  • A relatively minor contest that precedes a major one, especially in boxing 

adj
  • In preparation for the main matter; initial, introductory, preparatory. 

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