add vs string up

add and string up both are verbs.

Word	Noun	Adjective	Verb	Adverb
add	No	No	Yes	No
string up	No	No	Yes	No

As verbs, string up is a hyponym of add; that is, string up is a word with a more specific, narrower meaning than add:

add: make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of
string up: add as if on a string

add (verb)	string up (verb)
make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of	add as if on a string
make an addition by combining numbers	kill by hanging
determine the sum of
state or say further
bestow a quality on
constitute an addition