One of the important things about english is what kind of setting it's written or spoken in. That isn't very complicated in defining. It could be formal, informal, casual, business, and so on. Those are some important differences. One of the words for spoken language in english is called colloquial. Meaning language as it is communicated with cultural aspects and other factors. Which is different than literal grammar or phrasing. Just some advice for english as I'm trying to learn vietnamese and I'm not sure of how those kind of differences relate.