How a MO is diff from Sub inventory transfer?

MO generally are the request of movement of items in one organization. It may be of from 3 sources, MO requisition, Replenish MO, Pick Wave MO. MO can be MO Issue which will issue the item from the location and MO transfer which ll transfer the item to another location.

The difference between move order transfer and sub inventory transfer is In move orders, you can have an approval so you are not simply "taking" material from a sub inventory that is under someone else's control.

Also, move orders create allocations. So you can place hold on the material with the intention of picking it up a little later. In sub inventory transfer, there is no reservation / allocation. So until you actually pick up the material and perform the transaction, someone else can claim the material.