wake vs sit up

wake is a noun but sit up is not a noun.

Word	Noun	Adjective	Verb	Adverb
wake	Yes	No	Yes	No
sit up	No	No	Yes	No

As verbs, sit up is a hyponym of wake; that is, sit up is a word with a more specific, narrower meaning than wake:

Other hyponyms of wake include stay up.

wake (noun)	sit up (noun)
a vigil held over a corpse the night before burial
the wave that spreads behind a boat as it moves forward
the consequences of an event (especially a catastrophic event)

wake (verb)	sit up (verb)
be awake, be alert, be there	not go to bed
stop sleeping	change to an upright sitting position
cause to become awake or conscious
to alert someone to something
arouse or excite feelings and passions