headscarf vs hijab

headscarf

noun
  • A more or less square piece of material worn over the head, typically by women, often to protect the hair, or for religious reasons. 

hijab

noun
  • A traditional headscarf worn by Muslim women, covering the hair and neck. 

  • The practice, among Muslim women, of covering the body after the age of puberty in front of non-related adult males. 

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