I have installed Windows 10 in three different systems of mine. The first system, I use as a Windows Insider & upgraded from the RTM insider build 10240 by regular Windows updates & patches. The build string of this first system is: 10240.16393.amd64fre.th1_st1.150717-1719 In my second system, I upgraded from my original Windows 8.1 Pro via Windows update & the build string is as follows 10240.16393.amd64fre.th1_st1.150717-1719 But, in my 3rd system, I downloaded the 'MediaCreationToolx64' from the official website & download the Windows 10 & convert it into ISO file format using the same tool & made a clean installation after upgrading via windows update & then got the following build string 10240.16384.amd64fre.th1.150709-1700 So, there goes my question that why it is different? What I can presume is that the files that downloaded & converted into the ISO via media creation tool is comparatively old may be. I haven't tried any Wzor leaked ISO or the tech branch ISO or the MSDN ISO. So can anyone tell me anything about this? Has anyone tried/installed those 3 ISO (Wzor, MSDN & TechBranch) and can tell me what's the build string for those? Also, I don't know what's the actual difference between the Media creation tools (converted ISO), MSDN ISO & tech Branch ISO. Anyone who know, please clarify. I request everyone who've using Win10 to take a look at this issue & help/discuss. Thanks.