directional vs guideline

directional

noun
  • Something that indicates direction, such as a vehicle's turn signal. 

adj
  • Indicating direction. 

  • Of or relating to guidance or help. 

guideline

noun
  • A light line, used in lettering, to help align the text. 

  • A plan or explanation to guide one in setting standards or determining a course of action. 

  • A non-specific rule or principle that provides direction to action or behaviour. 

  • He considered the Ten Commandments more as a guideline than a requirement. 

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