Good Receipt with Inbound and MIGO

Hi everyone

When I create a PO to purchase material, I use 2 cases:

     - PO -> release PO -> create Inbound Delivery ->Good receipt (MIGO) ->Invoice -> Payment to vendor.

     - PO -> Good receipt (MIGO) ->Invoice -> Payment to vendor.

In 2 cases, the FI documents show nothing difference. So, 2 why we have to create IBD ???