back end vs vanguard

back end

noun
  • The processing of spent fuel from a nuclear reactor into reusable materials. 

  • That part of a hardware or software system that is farthest from the user; the internals rather than the user interface. 

  • The latter end of any given time, especially the latter part of the year; autumn; late autumn. 

  • Money paid on a contingent deferred basis, for example, as a proportion of the profits or revenue of a work. 

  • The rear, back, or unseen portion (of something). 

vanguard

noun
  • The person(s) at the forefront of any group or movement. 

  • The leading units at the front of an army or fleet. 

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