nitpick vs pick apart

nitpick and pick apart both are verbs.

Word	Noun	Adjective	Verb	Adverb
nitpick	No	No	Yes	No
pick apart	No	No	Yes	No

As verbs, pick apart is a hypernym of nitpick; that is, pick apart is a word with a broader meaning than nitpick:

nitpick: be overly critical; criticize minor details
pick apart: find fault with; express criticism of; point out real or perceived flaws

Other hypernyms of nitpick include criticise, criticize, knock.

nitpick (verb)	pick apart (verb)
be overly critical; criticize minor details	find fault with; express criticism of; point out real or perceived flaws