knowing vs apprehension

knowing and apprehension both are nouns.

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

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

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

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