What is the author's style in Sourcery by Terry Pratchett?

The language and the meaning in the story takes on a different style with each character. Creosote speaks largely in poetry that has a very odd meaning while most of the wizards are much more refined in their speaking. The overall effect is very relaxed and easy to read. There are certain characters that have a distinct attribute to their style that indicates who is speaking. Death speaks only in capital letters but his words are never in quotation marks.