I'm a bit confused regarding Parts vs Products. 

Example: I have a plating tank that is used for dipping metal products in.  I am assuming that that is a "product", and the asset would be any "instance" of that product.  For example, Tank #37278 at location "ABC" would be the asset, and the product would simply be "Plating Tank".

However when I go to "service and parts", the product "Plating Tank" is listed.  But it is not a "part".

Another example: If I have a car, it is the product.  The parts are the parts of that car.  If I look up "service and parts", the product "car" should not show up there.

So my question is what is the difference between parts and products and how do we differentiate them?  And why do products show up there?