precautionary vs precautional

precautionary and precautional both are adjectives.

Word	Noun	Adjective	Verb	Adverb
precautionary	No	Yes	No	No
precautional	No	Yes	No	No

As adjectives, precautionary and precautional are synonyms defined as:

precautionary and precautional: taken in advance to protect against possible danger or failure

precautionary (adjective)	precautional (adjective)
taken in advance to protect against possible danger or failure	taken in advance to protect against possible danger or failure