What is the different between grammar and structure?

In everyday usage, the Words are often used as synonyms. Technically, however, "grammar" simply means any system of organizing symbols into meaningful strings. In the case of human language, "grammar" means the entire system (from the sound system and the meaning system to the morphological system and the syntactic system) by which humans can express ideas in a language, or in language generally. "Structure" is perhaps a close synonym of "syntax," which refers to the hierarchies of Words that form clauses and sentences.