Why would code being a tree rather than a string necessarily differentiate it from other types of data? Surely, one could have non-code data that were also tre

Why would code being a tree rather than a string necessarily differentiate it from other types of data? Surely, one could have non-code data that were also trees (think, just to pick a concrete example, of coded natural language data which are naturally represented as trees). I thought the point in lisp was that the syntax for non-code data and code are the same so treating code as data (and thinking about code as data) is easier than in many other programming languages.