all-important vs important

all-important and important both are adjectives.

Word	Noun	Adjective	Verb	Adverb
all-important	No	Yes	No	No
important	No	Yes	No	No

all-important (adjective)	important (adjective)
of the greatest importance	of great significance or value
	of extreme importance; vital to the resolution of a crisis
	important in effect or meaning
	having or suggesting a consciousness of high position
	having authority or ascendancy or influence