When one is installing Windows 7, one is required to enter a Windows 7 Product Key. The product key determines the edition of the Windows, features to unlock and activate & the type & distribution channel of the license.
Types of Windows 7 Consumer Keys
There are 4 types of retail consumer keys for Windows 7:
- Retail key: This key comes with a retail box or download copy of Windows 7, and can be used for a clean install or upgrade.
- Retail Upgrade key: This key comes with a reduced-price upgrade only version of Windows 7 & can be used for upgrade only.
- OEM COA Non-SLP key: This is the regular OEM key without the special BIOS check. This type of key is provided with copies of Windows marked for purchase with a new PC only.
- OEM SLP key: This key is used for OEM computers that use BIOS-locked activation, used by large PC manufacturers.
These keys are generally supported for use with retail or OEM installation media.
Apart from these, there are of course, several types of volume licensing keys too for enterprise level machines.
Additional read: What do the different types of Microsoft Product Keys means ?