Apocryphal is an adjective used to describe something, usually a text or tale, as being widely known and most likely untrue. The origins of such works are usually in doubt or completely unknown.
The adverb form is apocryphally. The noun form is apocrypha. The term is not capitalized unless it is discussing specific works that have been excluded from the Bible. Those works are part of the Apocrypha and are Apocryphal. Other texts can be Apocryphal if they resemble these specific writings.
Canonical is the adjective used to describe the writings that are included in the Bible, or any other official religious text. Other fields use the term to designate something as important, officially endorsed, or relating to the canon. The canon of an organization is the set of accepted laws and rules. One can have a canon of scripture.
The funny thing about the old adages and apocryphal tales of woe that older folks spin when talking to us youngsters — I used to walk uphill to school both ways, etc. — is that they’re never true. [Cleveland Scene Weekly]
We hear, apocryphally, that Dorsey wanted something beyond the text of Twitter and the six-second loop of Vine to capture the full spectrum of what was going on around him. [Tech Crunch]
I fully expect what follows, of course, to be immediately dismissed by many as heresy, apocrypha, or unsubstantiated nonsense. [Napa Valley Register]
The Royal Spanish Academy, which produces the official Spanish-language dictionary, has been holding a funeral service in the convent every year since 1861 to commemorate the author of Spain’s canonical work. [The Wall Street Journal]