bomber vs warplane

bomber and warplane both are nouns.

Word	Noun	Adjective	Verb	Adverb
bomber	Yes	No	No	No
warplane	Yes	No	No	No

As nouns, warplane is a hypernym of bomber; that is, warplane is a word with a broader meaning than bomber:

Other hypernyms of bomber include aeroplane, airplane, plane, military plane.

bomber (noun)	warplane (noun)
a military aircraft that drops bombs during flight	an aircraft designed and used for combat
a large sandwich made of a long crusty roll split lengthwise and filled with meats and cheese (and tomato and onion and lettuce and condiments); different names are used in different sections of the United States
a person who plants bombs