main road vs route

main road and route both are nouns.

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

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

Other hypernyms of main road include road.

main road (noun)	route (noun)
a major road for any form of motor transport	an open way (generally public) for travel or transportation
	an established line of travel or access

main road (verb)	route (verb)
	send via a specific route
	divert in a specified direction
	send documents or materials to appropriate destinations