grasp vs get onto

grasp is a noun but get onto is not a noun.

Word	Noun	Adjective	Verb	Adverb
grasp	Yes	No	Yes	No
get onto	No	No	Yes	No

As verbs, get onto is a hyponym of grasp; that is, get onto is a word with a more specific, narrower meaning than grasp:

Other hyponyms of grasp include figure, catch on, cotton on, get it, get wise, latch on, tumble, twig, intuit, digest.

grasp (noun)	get onto (noun)
the act of grasping
an intellectual hold or understanding
understanding of the nature or meaning or quality or magnitude of something
the limit of capability

grasp (verb)	get onto (verb)
get the meaning of something	understand, usually after some initial difficulty
hold firmly