Orthodox Jew vs Jew

Orthodox Jew and Jew both are nouns.

Word	Noun	Adjective	Verb	Adverb
Orthodox Jew	Yes	No	No	No
Jew	Yes	No	No	No

As nouns, Jew is a hypernym of Orthodox Jew; that is, Jew is a word with a broader meaning than Orthodox Jew:

Orthodox Jew: Jew who practices strict observance of Mosaic law
Jew: a person belonging to the worldwide group claiming descent from Jacob (or converted to it) and connected by cultural or religious ties

Other hypernyms of Orthodox Jew include Hebrew, Israelite.

Orthodox Jew (noun)	Jew (noun)
Jew who practices strict observance of Mosaic law	a person belonging to the worldwide group claiming descent from Jacob (or converted to it) and connected by cultural or religious ties