step in vs interpose

step in and interpose both are verbs.

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

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

step in and interpose: get involved, so as to alter or hinder an action, or through force or threat of force

Other synonyms of step in include interfere, intervene.

step in (verb)	interpose (verb)
get involved, so as to alter or hinder an action, or through force or threat of force	to insert between other elements
act as a substitute	to put forth by way of intervention
	be or come between
	get involved, so as to alter or hinder an action, or through force or threat of force