Some online shops follow these guidelines (case A):
- Let user enter a billing address.
- Have a checkbox "Shipping address same as billing".
Some other online shops do it just the other way (case B):
- Let user enter a shipping address.
- Have a checkbox "Billing address same as shipping".
In case A, it seems that the primary view of the checkout workflow is to generate an invoice, whereas in case B the checkout process is seen as a step in the workflow to finally ship the actually product being ordered to the customer.
Is there any real reason to prefer case A or case B?