Typically the term ‘canon’ refers to a collection of texts that are definitively ‘closed’ and for this reason immutable and proclaimed as such by an official religious authority. This is the case with the Christian Bible, for example, but it is not the same in Buddhism. The Pali canon could be called ‘closed’ but it only became so after centuries of modification and dispute. It is ‘settled’ but more as a result of time than official intervention.
Another distinct feature here is the multiplicity of canons. We find three canons at the present time and these correspond to the three main branches of Buddhism: Theraveda, Mahayana, and Tibet.