First a .dotm or .dotx template, not .dot unless people with Word versions earlier than 2007.

With that said, the thing that interests most people who produce templates for other to use is that when the user double-clicks on it, the template is not changed or opened. A new document is created automatically.

Templates can be stored effectively in the Workgroup Templates Folder and accessed using File > New (although that has gotten harder, see here).

Templates can hold building blocks, documents cannot. A template can hold alternate boilerplate language as building blocks, custom textboxes, custom headers and footers, and general AutoText. A document cannot be a container for these.

Basically, templates are designed to be used to create other documents. Documents are not.