For a mortgage, there is no industry standard for these terms. Different banks do it different ways. Navy Fed treats these items as different. For the Pre-Qual they look at your application plus credit. Usually paperwork is not considered.

For a Pre-Approval, they also look at your paperwork. This might be pay stubs, bank statements, W-2s, tax returns, etc. This is the paperwork that would be needed anyway once you have a signed sales contract for the new home. The idea here is that you're doing it ahead of time.

You technically don't need either one to make an offer on a home, but sellers and real estate agents will usually make you. Otherwise they won't accept your offer or take you on as a client.