Why don't the boot orders in PowerShell and Hyper-V Manager match?

I've been experimenting with making changes to a hyper-v VM's boot order with the Set-VMFirmware -BootOrder CmdLet.

The boot order shown in Hyper-V Manager's firmware now shows a different boot order from Powershell.  Hyper-V Manager shows this:

While PowerShell Shows this:

Why is PowerShell and Hyper-V Manager showing two different boot orders?