Fixture is an item that holds a part to aid in the performance of an process. Fixtures may or may not include guides or templates as attachable or perninate parts of said fixture.
Guides are items used to guide a tool. a guide can be considered a template or a template can be considered a guide of sorts
Templates are items use to aid accuratly and repeditivly location of processes.
This is in the manufacturing engineering world the basic definition.
If you are really having this debate in your shop; questioning if an item is a fixture, template or guide; then you really need to be building a lot more "tooling" (a word that describes all the above) and debaiting far less
