shop vs comparison-shop

shop is a noun but comparison-shop is not a noun.

Word	Noun	Adjective	Verb	Adverb
shop	Yes	No	Yes	No
comparison-shop	No	No	Yes	No

As verbs, comparison-shop is a hyponym of shop; that is, comparison-shop is a word with a more specific, narrower meaning than shop:

Other hyponyms of shop include antique, window-shop.

shop (noun)	comparison-shop (noun)
a course of instruction in a trade (as carpentry or electricity)
a mercantile establishment for the retail sale of goods or services
small workplace where handcrafts or manufacturing are done

shop (verb)	comparison-shop (verb)
give away information about somebody	compare prices for a given item
do one's shopping
shop around; not necessarily buying
do one's shopping at; do business with; be a customer or client of