So you mean the product keys are slipsteamed within the .iso(helo by those 2 fiels) with some way that is why its not requiered at instalaltion time?
No they magically are generated from the Windows installation media. This makes it so I can say Avada Kedavra and make it all work perfectly. The Pid.txt is not a slipstreamed. Stop using the word slipstreamed. You're banned from using the word slipstreamed. They are included in the ISO file at the discretion of MS or in this case we call them GVLK keys which are included at the install of windows. They are overridden with the pid.txt. However seeing as we have not had any official ISOs in some time this is probably the result of a frankenbuild. Now I'm going to educate you. What happens with the pid.txt is basically just overriding the GVLK much like an unattended install in product key land.
This build doesn't work very well on an MSI GE60 Appache Pro. I do an upgrade and there is no mouse cursor on the screen. Then I do a clean install and it fails to show the start menu.
There are numerous build labs, Impressive and Winmain are separate. The latest Impressive build lab build is the one we just got, 10074, and the latest Winmain one is 10.0.10109.0.winmain.150426-0137. The earliest 10x1xx build being 10.0.10100.0.winmain.150415-1934. So, 10074 Impressive is newer despite having a lower build number. In answer to your question, therefore, neither.
maybe is your windows version then, because there is no issues with Aero Glass in Windows 7 with AMD or NVIDIA, only few INTEL graphics presented issues few years ago, but Intel already fixed the issue with new drivers.
They sure are trying to get people to send them every bit of information about your system that they can get. Customized settings used to be a big button, now it's just a text link. Losing transparency (as in how they are collecting data). And how about this little error: I did a clean install from the "official" 10074 iso, Updates failed, So called start menu just opens whenever it wants to. Just plain junk build. Everyone was pushing them to roll out new builds faster, and now they are just rolling out buggy builds.
I installed this build from scratch in a VHDX. All I can say is that I find build 10056 more stable than this one. There's a slow answer to all requests especially when clicking on start menu and opened apps. That's maybe just an impression but it's not a good one at the moment.