availability vs accessibility

availability and accessibility both are nouns.

Word	Noun	Adjective	Verb	Adverb
availability	Yes	No	No	No
accessibility	Yes	No	No	No

As nouns, availability and accessibility are synonyms defined as:

availability and accessibility: the quality of being at hand when needed

Other synonyms of availability include availableness, handiness.

availability (noun)	accessibility (noun)
the quality of being at hand when needed	the quality of being at hand when needed
	the attribute of being easy to meet or deal with