superhighway vs highway

superhighway and highway both are nouns.

Word	Noun	Adjective	Verb	Adverb
superhighway	Yes	No	No	No
highway	Yes	No	No	No

As nouns, highway is a hypernym of superhighway; that is, highway is a word with a broader meaning than superhighway:

Other hypernyms of superhighway include main road.

superhighway (noun)	highway (noun)
a broad highway designed for high-speed traffic	a major road for any form of motor transport
an extensive electronic network (such as the internet) used for the rapid transfer of sound and video and graphics in digital form