intensify vs step up

intensify and step up both are verbs.

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

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

Other synonyms of intensify include escalate.

intensify (verb)	step up (verb)
become more intense	increase in extent or intensity
make more intense, stronger, or more marked	speed up
increase in extent or intensity	make oneself visible; take action
make the chemically affected part of (a negative) denser or more opaque in order produce a stronger contrast between light and dark