A Job Template is a tool that can be used to pre-fill specifications on an item more quickly. It provides a base for setting up similar items and products.
ie. A template could be created for an 8.5x11 flyer. This template would be setup with a press, stock, imposition, etc. This template can then be added to an order, quote, or product and customized for the customer.
For more information on job templates, see Settings - Job Templates.
A Product is essentially a pre-made job item that can be used for orders internally, online, or on POS. When creating a product, a job template can be used to pre-fill specifications during setup but it is not necessary. It can also be setup with files, tasks, notes, outsourced vendor, etc.
ie. A product is created using the template for 8.5x11 flyer and customized (with files, stock, press, overridden pricing, etc) specifically for a customer. It is then added to that customer's online portal as a product item they can order regularly.
Note: Once a template has been added to a product item, changes made to the template will not live-up date to the product. This is to ensure that pricing changes are not applied to a product that has already had custom pricing applied to it.
For more information on products, see Settings - Products.