brownie vs sandman

brownie and sandman both are nouns.

Word	Noun	Adjective	Verb	Adverb
brownie	Yes	No	No	No
sandman	Yes	No	No	No

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

brownie: (folklore) fairies that are somewhat mischievous
sandman: an elf in fairy stories who sprinkles sand in children's eyes to make them sleepy

Other hyponyms of brownie include leprechaun.

brownie (noun)	sandman (noun)
square or bar of very rich chocolate cake usually with nuts	an elf in fairy stories who sprinkles sand in children's eyes to make them sleepy
(folklore) fairies that are somewhat mischievous