important vs all-important

important and all-important both are adjectives.

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

important (adjective)	all-important (adjective)
of great significance or value	of the greatest importance
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