beltway vs main road

beltway and main road both are nouns.

Word	Noun	Adjective	Verb	Adverb
beltway	Yes	No	No	No
main road	Yes	No	No	No

As nouns, main road is a hypernym of beltway; that is, main road is a word with a broader meaning than beltway:

beltway: a highway that encircles an urban area so that traffic does not have to pass through the center
main road: a major road for any form of motor transport

Other hypernyms of beltway include highway.

beltway (noun)	main road (noun)
a highway that encircles an urban area so that traffic does not have to pass through the center	a major road for any form of motor transport