species vs variety

species

noun
  • A category in the classification of organisms, ranking below genus; a taxon at that rank. 

  • A group of plants or animals having similar appearance. 

  • A mineral with a unique chemical formula whose crystals belong to a unique crystallographic system. 

  • Either of the two elements of the Eucharist after they have been consecrated. 

  • Visible or perceptible presentation; appearance; something perceived. 

  • A component part of compound medicine; a simple. 

  • A particular type of atom, molecule, ion or other particle. 

  • Type or kind. (Compare race.) 

  • Coin, or coined silver, gold, or other metal, used as a circulating medium; specie. 

variety

noun
  • A rank in a taxonomic classification below species and (if present) subspecies, and above form; hence, an organism of that rank. 

  • The total number of distinct states of a system; also, the logarithm to the base 2 of the total number of distinct states of a system. 

  • An animal or plant (or a group of such animals or plants) with characteristics causing it to differ from other animals or plants of the same species; a cultivar. 

  • In universal algebra: an equational class; the class of all algebraic structures of a given signature, satisfying a given set of identities. 

  • A specific form of a language, neutral to whether that form is an accent, dialect, register, etc., and to its prestige level; an isolect or lect. 

  • A collection or number of different things. 

  • The kind of entertainment given in variety performances or shows; also, the production of, or performance in, variety performances or shows. 

  • A deviation or difference. 

  • A stamp, or set of stamps, which has one or more characteristics (such as colour, paper, etc.) differing from other stamps in the same issue, especially if such differences are intentionally introduced. 

  • The quality of being varied; diversity. 

  • A specific variation of something. 

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