Looking for a word which means "relating to the order in which things are written down or expressed"

I think the word you are looking for is "respectively."

Ordinal

In the absence of any specific qualifier such as lexical or chronological, it would probably be just ordinal I guess.

You might get away with "precedence" or "priority", though of course neither refers to this specific case.

"Subsequence" or "posteriority" refer to something that follows something else, with "precedence", "antecedence" or "anteriority" working in the other direction.

Are you allowed to coin a term yourself, if you can't find one? Could languages be ordoverborically different? :-)

Have a look at the WP Word Order page for some hints at how this gets expressed by others.

The word is syntactically, from:

syntax : 1. (Linguistics) the branch of linguistics that deals with the grammatical arrangement of words and morphemes in the sentences of a language or of languages in general

Your sentence becomes:

English and French are syntactically different because in English one says "blue car" but in French it is "auto bleu".