I'm not sure I agree. Certainly there are differences other than syntax, but that doesn't mean syntax is irrelevant. For instance, would Clojure programmers use maps as much if there was no syntax for map literals?

Syntax determines what parts of a language are within easy reach, and therefore affects how programmers use the language. Tools that a syntax make easy are used often; tools that syntax makes hard are used infrequently. This indirectly impacts how a piece of software is designed.