monger vs costermonger

monger and costermonger both are nouns.

Word	Noun	Adjective	Verb	Adverb
monger	Yes	No	Yes	No
costermonger	Yes	No	No	No

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

monger: someone who purchases and maintains an inventory of goods to be sold
costermonger: a hawker of fruit and vegetables from a barrow

monger (noun)	costermonger (noun)
someone who purchases and maintains an inventory of goods to be sold	a hawker of fruit and vegetables from a barrow

monger (verb)	costermonger (verb)
sell or offer for sale from place to place