deferment vs deferral

deferment

noun
  • An act or instance of deferring or putting off. 

  • Officially sanctioned postponement of compulsory military service. 

deferral

noun
  • An act of deferring, a deferment. 

  • An accrual. 

  • A prepayment. 

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