Yes, Woodward.
In major part of China, the written Chinese is the same except for some special wordings and slangs. However, as far as spoken Chinese is concerned, it is greatly different, even each separate village has its own pronunciation. In China, it's called "Fang Yan", a special system of pronouncing.
In some districts of minority folks in China, people are really using "different" languages against Mandarin. It is the right of the minority folks in China, to use their own languages in daily life.
Under such situation, sometimes, the northern people do not understand the southern and vice versa.