The different part numbers refer to the same PXIe-1073 chassis. One part number is a bundle package that includes a PCIe card and MXI cable. The other part number is simply the chassis by itself.
781161-01: NI PXIe-1073 Chassis, PCIe-8361, 3m Cable
781163-01: NI PXIe-1073 Chassis
The PXIe-1073 chassis does come with an integrated MXI-Express controller.