contribute vs add

contribute and add both are verbs.

Word	Noun	Adjective	Verb	Adverb
contribute	No	No	Yes	No
add	No	No	Yes	No

As verbs, contribute and add are synonyms defined as:

Other synonyms of contribute include bestow, bring, impart, lend.

contribute (verb)	add (verb)
contribute to some cause	make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of
bestow a quality on	make an addition by combining numbers
provide	determine the sum of
be conducive to	state or say further
	bestow a quality on
	constitute an addition