motorway vs turnpike

motorway and turnpike both are nouns.

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

As nouns, turnpike is a hyponym of motorway; that is, turnpike is a word with a more specific, narrower meaning than motorway:

Other hyponyms of motorway include autobahn, autostrada, toll road.

motorway (noun)	turnpike (noun)
a broad highway designed for high-speed traffic	an expressway on which tolls are collected
	(from 16th to 19th centuries) gates set across a road to prevent passage until a toll had been paid