headscarf vs hijab

headscarf and hijab both are nouns.

Word	Noun	Adjective	Verb	Adverb
headscarf	Yes	No	No	No
hijab	Yes	No	No	No

As nouns, hijab is a hyponym of headscarf; that is, hijab is a word with a more specific, narrower meaning than headscarf:

headscarf: a kerchief worn over the head and tied under the chin
hijab: a headscarf worn by Muslim women; conceals the hair and neck and usually has a face veil that covers the face

Other hyponyms of headscarf include babushka, khimar.

headscarf (noun)	hijab (noun)
a kerchief worn over the head and tied under the chin	the custom in some Islamic societies of women dressing modestly outside the home
	a headscarf worn by Muslim women; conceals the hair and neck and usually has a face veil that covers the face