slip away vs sneak out

slip away and sneak out both are verbs.

Word	Noun	Adjective	Verb	Adverb
slip away	No	No	Yes	No
sneak out	No	No	Yes	No

As verbs, slip away and sneak out are synonyms defined as:

Other synonyms of slip away include slip out, sneak away, sneak off, steal away.

slip away (verb)	sneak out (verb)
for time to move forward	leave furtively and stealthily
leave furtively and stealthily