all right vs very well

all right is an adjective but very well is not an adjective.

Word	Noun	Adjective	Verb	Adverb
all right	No	Yes	No	Yes
very well	No	No	No	Yes

As adverbs, all right and very well are synonyms defined as:

all right and very well: an expression of agreement normally occurring at the beginning of a sentence

Other synonyms of all right include alright, fine, OK.

all right (adjective)	very well (adjective)
being satisfactory or in satisfactory condition

all right (adverb)	very well (adverb)
an expression of agreement normally occurring at the beginning of a sentence	quite well
without doubt (used to reinforce an assertion)	an expression of agreement normally occurring at the beginning of a sentence
in a satisfactory or adequate manner