differentiate vs retrofit

differentiate

verb
  • To make different; to change, modify. 

  • To (cause to) go through a process of development called differentiation; to make or become different in form or function. 

  • To recognize a distinction or difference between two things. 

  • To perceive the difference between things; to discriminate. 

  • To calculate the derivative of a function. 

  • To calculate the differential of a function of multiple variables. 

  • To teach a lesson in multiple different ways in order to meet the needs of more or less advanced students. 

noun
  • Something that has been differentiated or stratified. 

retrofit

verb
  • To give new characteristics or make alterations (to someone or something) to suit them to changed circumstances. 

  • To supply (a device, structure, etc.) with new components or parts that were not previously available or installed; to modernize. 

  • Synonym of backport (“to retroactively supply a fix or feature to a previous version of a software product at the same time or after supplying it to the current version.”) 

  • To supply a device, structure, etc., with new components or parts that were not previously available or installed. 

  • To add or substitute (new components or parts) that were not previously available for or installed in a device, structure, etc. 

noun
  • An act of supplying a device, structure, etc., with new components or parts that were not previously available or installed; a retrofitting. 

  • A change made to a device, structure, etc., by introducing components or parts that were not previously available or installed. 

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