turboprop vs propeller plane

turboprop and propeller plane both are nouns.

Word	Noun	Adjective	Verb	Adverb
turboprop	Yes	No	No	No
propeller plane	Yes	No	No	No

As nouns, propeller plane is a hypernym of turboprop; that is, propeller plane is a word with a broader meaning than turboprop:

turboprop: an airplane with an external propeller that is driven by a turbojet engine
propeller plane: an airplane that is driven by a propeller

turboprop (noun)	propeller plane (noun)
an airplane with an external propeller that is driven by a turbojet engine	an airplane that is driven by a propeller