Spoken language and its grammar has been robustly discussed in the field of Korean education as well as various language studies in recent years. It is possible to utilize written and spoken corpora after a large amount of corpora were built up and corpus linguistics was paid attention to by a lot of researchers in the late 1990s and early 2000s. It is the time to review the relations not only between spoken and written language but also between spoken and written language grammar. The primary purpose of the study is to answer the two crucial questions with regard to spoken language in the field of Korean education. First, how can we tell the difference between spoken and written language or spoken and written language grammar? Second, how can we detect the spoken language features or orality in the basis of the analysis of corpora? To answer these questions, the usages and the distributions of various language structures which are assumed to be under the category of the spoken language have been analyzed. In particular, the distributions of written and spoken forms of postpositions, endings, pronouns, exclamations, adverbs, and dependency nouns were compared and the following conclusions can be drawn from the present study. The relation between spoken and written language is neither contrastive nor exclusive. Rather, their relation is different aspects of one language depending on a media or a genre. In some cases, the division of "spoken language - co-activation from both languages - written language" can be decided by the principles of composing words or utterances. However, in the most cases, the division of them is the matter of the degree. It is almost impossible to find pure spoken language and grammar or pure written language and grammar. In other words, it seems reasonable that literacy and orality cannot be divided by the specific sets of words such as endings and postpositions but by aspects of using each lexeme and grammar. As a result, it is important to understand that the ratio of spoken language to written language is affected by genres, types, or registers in teaching-learning of combinations of words, and descriptions and educations of grammar rules.