turnpike vs superhighway

turnpike and superhighway both are nouns.

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

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

Other hypernyms of turnpike include expressway, freeway, motorway, pike, state highway, throughway, thruway.

turnpike (noun)	superhighway (noun)
an expressway on which tolls are collected	a broad highway designed for high-speed traffic
(from 16th to 19th centuries) gates set across a road to prevent passage until a toll had been paid	an extensive electronic network (such as the internet) used for the rapid transfer of sound and video and graphics in digital form