self-knowledge vs apprehension

self-knowledge and apprehension both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-knowledge	Yes	No	No	No
apprehension	Yes	No	No	No

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

Other hypernyms of self-knowledge include discernment, savvy, understanding.

self-knowledge (noun)	apprehension (noun)
an understanding of yourself and your goals and abilities	the act of apprehending (especially apprehending a criminal)
	the cognitive condition of someone who understands
	painful expectation
	fearful expectation or anticipation