fighter aircraft vs aeroplane

fighter aircraft and aeroplane both are nouns.

Word	Noun	Adjective	Verb	Adverb
fighter aircraft	Yes	No	No	No
aeroplane	Yes	No	No	No

As nouns, aeroplane is a hypernym of fighter aircraft; that is, aeroplane is a word with a broader meaning than fighter aircraft:

fighter aircraft: a high-speed military or naval airplane designed to destroy enemy aircraft in the air
aeroplane: an aircraft that has a fixed wing and is powered by propellers or jets

Other hypernyms of fighter aircraft include airplane, plane, military plane, warplane.

fighter aircraft (noun)	aeroplane (noun)
a high-speed military or naval airplane designed to destroy enemy aircraft in the air	an aircraft that has a fixed wing and is powered by propellers or jets