IS vs AS keywords for PL/SQL Oracle Function or Procedure Creation [duplicate]

Answer 1

I've never known there to be a difference. The Oracle documentation implies that they are synonyms:

The function body begins with the keyword IS (or AS) and ends with the keyword END followed by an optional function name.

Answer 2

Same as DISTINCT and UNIQUE in select statements. i.e, there is no material difference between 'IS' and 'AS'. Backwards compatibility and meeting standards