Syntax explains how sentences and texts should be formed. There are two categories of syntax that are similar to some extent but display a distinction between themselves as well. They are constituent structure and argument structure of the language. Thus, the constituent structure of the language is the set of rules according to which words are put together in phrases, and then both words and phrases are compiled into sentences. For example, the rule to put an adjective before the noun it describes is typical of English and is one of the constituents of its constituent structure, while in French or Spanish constituent structure presupposes placing an adjective after the noun. At the same time, argument structure in syntax is the set of rules according to which words are selected to make complete phrases. In other words, some verbs in English, mainly intransitive ones, need only one component, called argument, after them to complete a phrase (e. g. John came in.), while transitive verbs need two arguments to be put after them (e. g. Ray wrote a book), and ditransitive verbs are accompanied with three arguments (e. g. Linda sent the letter to John).
References
LING6910. (2008). Syntax. Foundations of Linguistics: Lecture 4.