big spender vs spender

big spender and spender both are nouns.

Word	Noun	Adjective	Verb	Adverb
big spender	Yes	No	No	No
spender	Yes	No	No	No

As nouns, spender is a hypernym of big spender; that is, spender is a word with a broader meaning than big spender:

Other hypernyms of big spender include scattergood, spend-all, spendthrift.

big spender (noun)	spender (noun)
one who spends lavishly and ostentatiously on entertainment	someone who spends money to purchase goods or services
	someone who spends money prodigally