Compound sentence refers to two sentences with similar structure, related content, adjacent writing and equal number of words, which are similar to antithetical sentences, but not as strict as antithetical sentences in phonology. Compound sentence can also be divided into neat sentences and untidy sentences, and untidy compound sentence may not fully meet the requirements in terms of structure and number of words. Prose is relative to parallel prose. In other words, except compound sentence, all sentences are prose sentences.
Parallel sentences existed in pre-Qin articles, but they didn't do it on purpose. Fu became popular only after it came into being in the Han Dynasty. In the Six Dynasties, it developed into a parallel style with four-character and six-character sentences, which were called "four wives and six wives tied together". After the middle Tang Dynasty, parallel prose declined, but people still use parallel prose in their articles, and it is not limited to four or six words. Generally speaking, an article only uses a few parallelism sentences, not a combination of parallelism sentences and prose sentences. Only a certain number of parallel sentences are used.