any vs either

any

det
  • One at all; at least one; at least one kind of; some; a positive quantity of. 

  • No matter what kind. 

pron
  • Any thing(s) or person(s). 

adv
  • To even the slightest extent, at all. 

either

det
  • Any one (of two). 

  • Each of two; both. 

conj
  • Introduces the first of two (or occasionally more) options or possibilities, the second (or last) of which is introduced by “or”. 

adv
  • As well. 

pron
  • One or the other of two people or things. 

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