stock trader vs dealer

stock trader and dealer both are nouns.

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

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

stock trader: someone who buys and sells stock shares
dealer: someone who purchases and maintains an inventory of goods to be sold

Other hypernyms of stock trader include bargainer, monger, trader.

stock trader (noun)	dealer (noun)
someone who buys and sells stock shares	a firm engaged in trading
	a seller of illicit goods
	the person who distributes the playing cards in a card game
	someone who purchases and maintains an inventory of goods to be sold
	the major party to a financial transaction at a stock exchange; buys and sells for his own account