step up vs rev up

step up and rev up both are verbs.

Word	Noun	Adjective	Verb	Adverb
step up	No	No	Yes	No
rev up	No	No	Yes	No

As verbs, step up and rev up are synonyms defined as:

step up (verb)	rev up (verb)
increase in extent or intensity	increase the number of rotations per minute
speed up	speed up
make oneself visible; take action