Syntactical vs. Syntactic

syntactic, related to syntax

of or relating to or conforming to the rules of syntax;

Example: ‘the syntactic rules of a language’;

Of, related to or connected with syntax.

Example: ‘The sentence “I saw he” contains a syntactic mistake.’;

Containing morphemes that are combined in the same order as they would be if they were separate words e.g. greenfinch

Of or pertaining to syntax; according to the rules of syntax, or construction.

of or relating to or conforming to the rules of syntax;

Example: ‘the syntactic rules of a language’;