exit vs step out

exit is a noun but step out is not a noun.

Word	Noun	Adjective	Verb	Adverb
exit	Yes	No	Yes	No
step out	No	No	Yes	No

As verbs, step out is a hyponym of exit; that is, step out is a word with a more specific, narrower meaning than exit:

exit (noun)	step out (noun)
the act of going out
an opening that permits escape or release
euphemistic expressions for death

exit (verb)	step out (verb)
pass from physical life and lose all bodily attributes and functions necessary to sustain life	go outside a room or building for a short period of time
lose the lead
move out of or depart from