How does the attributes relate to a sale?

I have template A (Shoe) with Variant B (Color Black) and C (Color Brown). The attributes and extra price config are set at the product.template level, but it appears the variants exist independent of the attributes and are not related. How do you define that variant B of Template A is black using the attributes?

When you create a sale order you add a product.product record, which contains no reference to attribute values. Can someone explain? How does one use the other pricing specified in the attributes? Is this functionality only for the ecommerce? There seems to be no references to the product attributes/special pricing in sale.py