What are the differences between Win7/Win8/Win8.1 system upgrade to win10 official version

1, upgrade from Win7/Win8/Win8.1 system to win10
If you are a Microsoft officially authorized user, then you can upgrade to win10 official version for free (such as win8 regular version can be upgraded to win10 ordinary Version) and permanent use;
If you are using an unauthorized version of win7.Win8, then you still need to purchase the license after upgrading the win10 system<2>2, upgrade from win10 preview to win10
preview can Upgrade directly, but if you want to use the official version after the upgrade, you will need to pay for the Windows 10 license. If you are willing to participate in the Windows Membership Program Test Preview, you do not need to purchase it.
3, genuine authorized win7/win8/win8.1 upgrade to Win10 preview version after upgrading win10 official version
According to Microsoft's instructions, this is also free upgrade and permanent use, but it is not clear, but we You can first go back to the previous windows version and then upgrade the official version of win10.
Note: Win10 member test users need to register to join, and the price may be that you will keep installing test updates, when Microsoft is a mouse.
Win7/Win8/Win8.1 system upgrade to win10 official version of the difference, originally Win7, Win8 can directly upgrade Win10, Win10 preview version to return to the original system. Now it's reversed. It seems that Windows still has preferential treatment for Win10 preview users who are willing to give them a mouse.