rev up vs step up

rev up and step up both are verbs.

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

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

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