Nothing to correct anshad, I agree
I had prepared my answer without seeing yours, I put it anyway
You need to read additional information about Windows To Go carloscape
you can Read this with the faq http://technet.microsoft.com/en-us/library/hh831833.aspx
Breifly and subject Win8.1 To Go works as the real Windows 8.1 but on a USB stick/disk rather than on an internal disk.
With some exception (ex: Internal disks are offline, Hibernate is disabled by default, Refreshing or resetting a Windows To Go workspace is not supported).
So it is a full windows 8.1 installation from install.wim on USB with flat file that allows to write data, registry ot to install apps and keep them for a future use.
It is supported Only on USB 3.0 drives that are certified and can start on USB 2.0 or USB 3.0 ports.
Even for test, I think you'll have trouble to run it on a USB2 stick of 1 Gb.
Win8.1SE works like others WinPE for users, with boot.wim mounted in RAM.
But it is not either a trully PE. Example:
Logon as administrator and not the system account like on all PE.
It does not use cmdline at startup and Winpeshl.exe (directly, I launch manually it after).
Otherwise, same, the registry or installed applications in Ram are not saved....
Without all components, it should run on PC a little old with 512 Mb Ram and with that a USB 2 stick of 512 Mb-1Gb.
Try one and the other and you will see they are really fully different for a completely different use.Edit:
I think, but it is feedback that will be able to confirm, there may be a real gain compared to others PE.
It is maybe a little longer at startup, I have not measured watch in hand.