twig vs grok

twig is a noun but grok is not a noun.

Word	Noun	Adjective	Verb	Adverb
twig	Yes	No	Yes	No
grok	No	No	Yes	No

As verbs, grok is a hypernym of twig; that is, grok is a word with a broader meaning than twig:

Other hypernyms of twig include apprehend, compass, comprehend, dig, get the picture, grasp, savvy.

twig (noun)	grok (noun)
a small branch or division of a branch (especially a terminal division); usually applied to branches of the current or preceding year

twig (verb)	grok (verb)
branch out in a twiglike manner	get the meaning of something
understand, usually after some initial difficulty