brainstorm vs apprehension

brainstorm and apprehension both are nouns.

Word	Noun	Adjective	Verb	Adverb
brainstorm	Yes	No	Yes	No
apprehension	Yes	No	No	No

As nouns, apprehension is a hypernym of brainstorm; that is, apprehension is a word with a broader meaning than brainstorm:

brainstorm: the clear (and often sudden) understanding of a complex situation
apprehension: the cognitive condition of someone who understands

Other hypernyms of brainstorm include discernment, savvy, understanding.

brainstorm (noun)	apprehension (noun)
the clear (and often sudden) understanding of a complex situation	the act of apprehending (especially apprehending a criminal)
	the cognitive condition of someone who understands
	painful expectation
	fearful expectation or anticipation

brainstorm (verb)	apprehension (verb)
try to solve a problem by thinking intensely about it