syntactic vs syntactical

syntactic and syntactical both are adjectives.

Word	Noun	Adjective	Verb	Adverb
syntactic	No	Yes	No	No
syntactical	No	Yes	No	No

As adjectives, syntactic and syntactical are synonyms defined as:

syntactic and syntactical: of or relating to or conforming to the rules of syntax

syntactic (adjective)	syntactical (adjective)
of or relating to or conforming to the rules of syntax	of or relating to or conforming to the rules of syntax