If that's not done, and the round ships without being pre-funded the round gets marked "BUYER FUNDED" in laser engraving.
Technically both are buyer funded. However, the former case it's confirmed that the proper amount of BTC is loaded and the hologram is in place over the private key before shipping.
If it's buyer funded after the buyer gets it technically they could fund a different amount than marked on the coin and there's no guarantee about the private key not being copied somewhere else. So, that's why those are marked as such.