circulate vs diffuse

circulate is not an adjective while diffuse is an adjective.

Word	Noun	Adjective	Verb	Adverb
circulate	No	No	Yes	No
diffuse	No	Yes	Yes	No

As verbs, circulate and diffuse are synonyms defined as:

circulate (adjective)	diffuse (adjective)
	(of light) transmitted from a broad light source or reflected
	spread out; not concentrated in one place
	lacking conciseness

circulate (verb)	diffuse (verb)
cause to become widely known	cause to become widely known
become widely known and passed on	spread or diffuse through
move around freely from person to person or from place to place	move outward
move through a space, circuit or system, returning to the starting point
cause to be distributed
cause to move in a circuit or system