Egyptian vs Copt

Egyptian and Copt both are nouns.

Word	Noun	Adjective	Verb	Adverb
Egyptian	Yes	Yes	No	No
Copt	Yes	No	No	No

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

Other hyponyms of Egyptian include Theban, Cairene, Nubian.

Egyptian (noun)	Copt (noun)
the ancient and now extinct language of Egypt under the Pharaohs; written records date back to 3000 BC	a member of the Coptic Church
a native or inhabitant of Egypt	an Egyptian descended from the ancient Egyptians

Egyptian (adjective)	Copt (adjective)
of or relating to or characteristic of Egypt or its people or their language