comme il faut vs decorous

comme il faut and decorous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
comme il faut	No	Yes	No	No
decorous	No	Yes	No	No

As adjectives, comme il faut and decorous are synonyms defined as:

Other synonyms of comme il faut include becoming, comely, seemly.

comme il faut (adjective)	decorous (adjective)
according with custom or propriety	characterized by propriety and dignity and good taste in manners and conduct
	according with custom or propriety