stamp dealer vs trader

stamp dealer and trader both are nouns.

Word	Noun	Adjective	Verb	Adverb
stamp dealer	Yes	No	No	No
trader	Yes	No	No	No

As nouns, trader is a hypernym of stamp dealer; that is, trader is a word with a broader meaning than stamp dealer:

stamp dealer: a dealer in stamps (whose customers are stamp collectors)
trader: someone who purchases and maintains an inventory of goods to be sold

Other hypernyms of stamp dealer include bargainer, dealer, monger.

stamp dealer (noun)	trader (noun)
a dealer in stamps (whose customers are stamp collectors)	someone who purchases and maintains an inventory of goods to be sold