reboot[.]pro/topic/21459-mistype-windows-10-pe/
The Windows To Go I've talked about is a full fledged Windows 10 Installation. When you boot to it on different hardware it goes through part of its setup routine, figuring out what drivers are necessary, & installing them. WinPE is a really minimal version of Windows that gives you a command line, but no desktop or apps etc. -- companies like Paragon & AOMEI use WinPE as the underpinning of their bootable USB sticks, automatically starting their app when WinPE starts.
WinBuilder projects like this however are hybrids that fit in between those 2 extremes. You get what *looks* like a fully functioning Windows install at 1st glance, but there's a limited number of apps included, & while you can usually install software, you have to do it every time it runs. Portable apps are cool -- using the portable VBox launcher I've run a full Windows VM.
These projects generally try to use generic driver packs so there's no driver installation, & the accompanying disk bloat to worry about. Personally I'd tend to skip the discussion on different boot methods, creating an ISO to use with rufus.
You will need to supply at least a Windows ISO, but if you join the Windows Insider Program -- just a simple sign-up -- you can get them here:
microsoft[.]com/en-us/software-download/windowsinsiderpreviewadvanced
Next week they'll hopefully have the RTM version available, which is the same version or build they'll release to everyone in April.