In the Products backend you are able to create catalog products and templates. Templates can be understood as internal templates in the backend, so you can easily create a new catalog product, if you already have a similar product. 

BUT you can also use a template as base for different catalog products and link it to these catalog products. Let's say you are having a lot of catalog products and some of these have the same layers and looks identical except of some layers. Then you can create a template with all layers that are the identical across specific catalog products and in the catalog product you can add the layers (image/text) that are unique for this catalog product.

Why should I do that?

The answer is quite simple. If you want to change the base of the catalog products, you only need to do that in the linked template. Instead of changing all catalog products separately and is a huge time-saver in the product management.

Okay cool, please show me how to do that!

First of all create a new template, you can do that in the "My Templates" tab by clicking the "New" button or in the "Catalog Products" tab by creating a template from an existing product. In the template add all views and layers that identical.

When you are done with the template setup, go to the "Catalog Products" tab and create a new product or select an existing one and click the relevant button to open the "Product Options".

In the product options you can select a template that you want to link with the catalog product.

Save the options and now your catalog product is linked to that template. If you open a view of this catalog product in the product builder, you will also see the layers from linked template in the canvas. An info message at the top will also tell you that the view is linked to a template.