Basically, they are core journals. There are great differences between A.B.C Let me briefly talk about the literature I am familiar with.
For example, if a literature professor in a university wants to obtain doctoral qualification next year, he must publish more than one A-class core article in the past few years, which is relatively difficult. Generally, there are 10 kinds of such core journals in China. Such as literary criticism, literary inheritance and literary contention.
Class B is relatively low-grade, and basically every province has this kind of publication.
Such as Nanjing Social Sciences, Hunan Social Sciences and Gansu Social Sciences.
Generally, doctoral graduates are required to publish more than two B-type papers before they are qualified to reply. If you evaluate associate professors and professors every year, you should publish at least 2-4 core B papers. It is not so easy to publish articles on it.
As for Class C, the grade will definitely be lower.