Using styles can greatly reduce the time it takes to format (and reformat ) your documents. If you work in an office, you can use styles to standardize the appearance of all the documents you and your co-workers generate. If you expect that styles will improve your quality of life, you will also benefit from templates.
Word provides templates for creating all kinds of documents. If you like one in particular, you can tweak it to make it your own. If you don't like Word's templates, or if none are designed for the type of documents you create, you can create a template from scratch so that it contains the exact text and formatting that you need. Templates can also store styles, AutoText entries, toolbars , and macros. Word gives you a variety of ways to access these items, regardless of what template they are stored in.