slip away vs move on

slip away and move on both are verbs.

Word	Noun	Adjective	Verb	Adverb
slip away	No	No	Yes	No
move on	No	No	Yes	No

As verbs, move on is a hypernym of slip away; that is, move on is a word with a broader meaning than slip away:

Other hypernyms of slip away include advance, go on, march on, pass on, progress.

slip away (verb)	move on (verb)
for time to move forward	move forward, also in the metaphorical sense
leave furtively and stealthily