double vs dual

double is a noun but dual is not a noun.

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

As adjectives, double and dual are synonyms defined as:

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

Other synonyms of double include duple.

As adjectives, double and dual are synonyms defined as:

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

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

double (noun)	dual (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

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

double (verb)	dual (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)