unfastened vs unbuttoned

unfastened and unbuttoned both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unfastened	No	Yes	No	No
unbuttoned	No	Yes	No	No

As adjectives, unfastened and unbuttoned are synonyms defined as:

unfastened (adjective)	unbuttoned (adjective)
not closed or secured	not buttoned
not buttoned	not under constraint in action or expression
not tied
affording unobstructed entrance and exit; not shut or closed