Start windows myself on the usb stick

Hello all the world, I live in Paris, I work every day with winbuilder software, it is really great, I am studying her scripts all
the days to better understand windows, Internet is the only software that I found which is able to boot a lightweight windows
from a usb stick or a cd, this software is my teacher. My dream would be to make myself a windows Lite (still on the same principle
that winbuilder, windows compresses in the boot.wim file system), I can myself from the windows cd-rom 8.1 extract the file
install.wim and boot.wim and edit the registry key and select the correct windows for then compress my new system files in
boot.wim file that I could boot from my usb stick, and all this without the help of winbuilder. For this I must know the boot process
windows exact, the keys to register that they must modify, delete or add, and the windows also files, system files, files dll, ect...
There is some command-line winbuilder Scrip that I don't understand, can you tell me the difference in windows startup 8.1 already
installed on the hard drive and start windows 8.1 installed on the usb stick (System directed by winbuilder, boot.wim), I know that bootmgr.exe
consults the bcd store located in boot/bcd, after consulting bootmgr.exe starts winload.exe, winload.exe load windows but winload.exe
load what exactly, is the difference between the hard drive and the usb key, thank you all the world...?

Hi

"Windows 8.1" itself is capable of running from a USB stick - it's called "Windows to Go".

http://www.microsoft.com/en-us/windows/enterprise/products-and-technologies/devices/windowstogo.aspx

Microsoft officially supports "Windows To Go" feature in "Enterprise" version only as it's the sole version of Windows which can be legally used on multiple computers. However any version of Windows 8 can be run from a USB stick but we need to manually prepare the stick ourselves - http://www.rmprepusb.com/tutorials/129

Thanks for your reply, you you talk to install windows 8.1 on the usb key, and not a load of the system on the ram.
me I'm looking for booting on the ram, with the boot.wim file, that rightly winbuilder, I'll add
a new topic by asking my question otherwise...