dual vs double

dual is not a noun while double is a noun.

Word	Noun	Adjective	Verb	Adverb
dual	No	Yes	No	No
double	Yes	Yes	Yes	Yes

As adjectives, dual and double are synonyms defined as:

dual and double: consisting of or involving two parts or components usually in pairs

Other synonyms of dual include duple.

As adjectives, dual and double are synonyms defined as:

dual and double: having more than one decidedly dissimilar aspects or qualities

Other synonyms of dual include three-fold, threefold, treble, two-fold, twofold.

dual (noun)	double (noun)
	a base hit on which the batter stops safely at second base
	raising the stakes in a card game by a factor of 2
	a quantity that is twice as great as another
	someone who closely resembles a famous person (especially an actor)
	a stand-in for movie stars to perform dangerous stunts

dual (adjective)	double (adjective)
consisting of or involving two parts or components usually in pairs	used of homologous chromosomes associated in pairs in synapsis
a grammatical number category referring to two items or units as opposed to one item (singular) or more than two items (plural)	used of flowers having more than the usual number of petals in crowded or overlapping arrangements
having more than one decidedly dissimilar aspects or qualities	having two meanings with intent to deceive
	large enough for two
	twice as great or many
	consisting of or involving two parts or components usually in pairs
	having more than one decidedly dissimilar aspects or qualities

dual (verb)	double (verb)
	increase twofold
	hit a two-base hit
	do double duty; serve two purposes or have two functions
	make or do or perform again
	bend over or curl up, usually with laughter or pain
	make a demand for (a card or suit)