A Full license allows a user to perform a clean installation of Windows 7 without any stipulations. A Full license may only be installed on one computer at a time. It is legal to move this license to a new PC, or to reinstall the OS when the motherboard has been changed. It is not necessary for the user to own any prior copy of Windows.Full licenses ship with installation media for 32-bit and 64-bit installations.
An OEM license come pre-installed on a new PC, or are purchased by system builders to bundle with new PCs. OEM licenses are Full editions restricted by a non-transference clause which states that the OS may only ever be installed on one computer. It is not legal to move an OEM license to a new PC. It is also not legal to reinstall the operating system if a new motherboard with a different chipset is installed.OEM licenses ship with installation media for 32-bit or 64-bit. You must purchase two separate DVDs if you want both ISAs.
An upgrade license allows a user to perform a clean installation of Windows provided he or she owns a valid, licensed copy of Windows 2000, Windows XP or Windows Vista. An Upgrade license may only be installed on one computer at a time. It is legal to move this license to a new PC, or to reinstall the OS when the motherboard has been changed. Once Windows 7 has been installed, it is not legal to use the valid copy of Windows 2000, Windows XP or Windows Vista on another system.
Note. If an Upgrade license is used to upgrade an OEM installation, the non-transference clause of the OEM license applies. It is not legal to install and then upgrade the OEM copy on another PC, or after a motherboard swap.
Upgrade licenses are cheaper because they do not allow a user to run more copies of Windows than they already own. Windows 7 has taken the place of another version of Windows. On the other hand, think of Upgrade licenses as something of a buyer loyalty program for those who have bought into Windows in the past.Upgrade licenses ship with installation media for 32-bit and 64-bit installations.
A Family Pack license is three Windows 7 Home Premium Upgrade licenses. All the rules and restrictions of an Upgrade license applies to the Family Pack, but it is an economical option for users who have to upgrade several computers. If you are a “Qualified Family Pack User”, you may install one copy of the software marked as “Family Pack” on three computers in your household for use by people who reside there. Those computers are the “licensed computers” and are subject to these license terms.
You are a Qualified Family Pack User if you obtained an upgrade license to Windows 7 Home Premium in a product labeled "Family Pack" on the product packaging and media.
If you do not know whether you are a Qualified Family Pack User, best contact the Microsoft affiliate serving your country.