apprehension vs knowing

apprehension and knowing both are nouns.

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

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

apprehension (noun)	knowing (noun)
the act of apprehending (especially apprehending a criminal)	a clear and certain mental apprehension
the cognitive condition of someone who understands
painful expectation
fearful expectation or anticipation

apprehension (adjective)	knowing (adjective)
	highly educated; having extensive information or understanding
	evidencing the possession of inside information
	characterized by conscious design or purpose
	alert and fully informed