riddle canon vs enigma canon

riddle canon and enigma canon both are nouns.

Word	Noun	Adjective	Verb	Adverb
riddle canon	Yes	No	No	No
enigma canon	Yes	No	No	No

As nouns, riddle canon and enigma canon are synonyms defined as:

riddle canon and enigma canon: a canon in which the entrances of successive parts were indicated by cryptic symbols and devices (popular in the 15th and 16th centuries)

Other synonyms of riddle canon include enigmatic canon, enigmatical canon.

riddle canon (noun)	enigma canon (noun)
a canon in which the entrances of successive parts were indicated by cryptic symbols and devices (popular in the 15th and 16th centuries)	a canon in which the entrances of successive parts were indicated by cryptic symbols and devices (popular in the 15th and 16th centuries)