They are not all installed by default. They may be quite different in different program versions. A Word document wizard is a sequence of dialogs, asking you to make choices and to answer questions. The wizard creates a document based on your answers. You can then make adjustments and corrections and add more text and graphics.
Wizards are simply great for documents with complex layouts like brochures and newsletters.
They save you a lot of time and aggravation. The word template is used in two ways. Technical - a document with a special format that can be used to create a new document, without risk of changing the one used as the template. General - any document that is used as a guide when creating a new document. A Word template can contain standard text and images that are intended to be part of every document made with the template.