step in vs deputise

step in and deputise both are verbs.

Word	Noun	Adjective	Verb	Adverb
step in	No	No	Yes	No
deputise	No	No	Yes	No

As verbs, step in and deputise are synonyms defined as:

Other synonyms of step in include deputize, substitute.

step in (verb)	deputise (verb)
get involved, so as to alter or hinder an action, or through force or threat of force	appoint as a substitute
act as a substitute	act as a substitute