know what's going on vs know what's what

know what's going on and know what's what both are verbs.

Word	Noun	Adjective	Verb	Adverb
know what's going on	No	No	Yes	No
know what's what	No	No	Yes	No

As verbs, know what's going on and know what's what are synonyms defined as:

Other synonyms of know what's going on include be on the ball, be with it, know the score.

know what's going on (verb)	know what's what (verb)
be well-informed	be well-informed