category vs department

category

noun
  • A group, often named or numbered, to which items are assigned based on similarity or defined criteria. 

  • A collection of objects, together with a transitively closed collection of composable arrows between them, such that every object has an identity arrow, and such that arrow composition is associative. 

department

noun
  • A specified aspect or quality. 

  • One of the divisions of instructions 

  • A territorial division; a district; especially, in France, one of the districts into which the country is divided for governmental purposes, similar to a county in the UK and in the USA. France is composed of 101 départements organized in 18 régions, each department is divided into arrondissements, in turn divided into cantons. 

  • A distinct course of life, action, study, or the like. 

  • A military subdivision of a country 

  • A part, portion, or subdivision. 

  • One of the principal divisions of executive government 

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