diagram vs histogram

diagram

verb
  • To represent or indicate something using a diagram. 

  • To schedule the operations of a locomotive or train according to a diagram. 

noun
  • A plan, drawing, sketch or outline to show how something works, or show the relationships between the parts of a whole. 

  • A functor from an index category to another category. The objects and morphisms of the index category need not have any internal substance, but rather merely outline the connective structure of at least some part of the diagram's codomain. If the index category is J and the codomain is C, then the diagram is said to be "of type J in C". 

  • Electrical diagrams show device interconnections. 

  • A graph or chart. 

histogram

verb
  • To represent (data) as a histogram. 

noun
  • A graphical display of numerical data in the form of upright bars, with the area of each bar representing frequency. 

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