>In short, the distinction is pretty arbitrary. Linguistically, the distinction is much more objective (also it's not always clear cut, because there are asymm

>In short, the distinction is pretty arbitrary. Linguistically, the distinction is much more objective (also it's not always clear cut, because there are asymmetries between speeches in terms of how understandable they are to each other) : two kinds of speech that are not inter-comprehensible are different languages. Dialects and sub-dialects are defined by isoglosses, see the map I link in my original post. Arabic is, much like Chinese, both a linguistic group and a language (Modern Standard Arabic).