pencil box vs pencil case

pencil box

noun
  • A container for stationery such as pencils, pens, rubber, correction fluid, etc. 

pencil case

noun
  • An object purposed to contain different stationery like pencil, rubber, correction fluid, etc. 

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