butty vs open sandwich

butty

noun
  • A sandwich, usually with a hot savoury filling in a breadcake. The most common are chips, bacon, sausage and egg. 

  • A miner who works under contract, receiving a fixed amount per ton of coal or ore. 

  • Friend. 

  • A workmate. 

open sandwich

noun
  • Any dish consisting of only one slice of bread, with any topping. 

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