subfamily vs subsection

subfamily

noun
  • A taxonomic category ranking between a family and a genus; formerly called a tribe 

  • A secondary or subordinate grouping. 

subsection

noun
  • An informal taxonomic category below section and above family. 

  • A defined part of a section. 

  • A subpart of a legal document such as law. 

  • A taxonomic rank below the section, but above the species. 

verb
  • To insert subsections (into some text, etc.). 

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