motorway vs throughway

motorway and throughway both are nouns.

Word	Noun	Adjective	Verb	Adverb
motorway	Yes	No	No	No
throughway	Yes	No	No	No

As nouns, motorway and throughway are synonyms defined as:

motorway and throughway: a broad highway designed for high-speed traffic

Other synonyms of motorway include expressway, freeway, pike, state highway, superhighway, thruway.

motorway (noun)	throughway (noun)
a broad highway designed for high-speed traffic	a broad highway designed for high-speed traffic