Difference between Product Key and Serial Number

You can think of the Serial Number as a VIN (Vehicle Identification Number) if that helps. You can think of it as a person's name. You can think of it as the bar code on a can of tuna. The Serial Number is an identifier for that product or object. If there was an issue with your particular object, product, or OS installation media, tracing the serial number could result in revealing a problem during production... as that serial number can be used to identify when and where something was manufactured. That's down to the date, time, and location in a particular production facility.

The Product Key... that's not a serial number. In this specific case (since cans of Tuna don't have Product Keys... unless you count the Can Opener) the Product Key is just that... a key. The installation (identified by the serial number) is locked, and must be unlocked to be used. To unlock (activate) it, you need the key.

A Serial Number can be publicly displayed. It can be openly available and searched. A Product Key must be kept out of the public eye and reach... which means you might say that a Serial Number is the number posted on your house or mailbox, while the Product Key is the key to your front door.

I used to think this was straight forward until last week when I had to call Microsoft for help to move a Visio license. The person I spoke with asked me for the Product Key and I gave it to her from my account licensing page. But, she kept saying the was the Serial Number and not the Product Key. I kept saying, "It says Product Key right next to the number!"

When I asked the next tech support guy explained that internally, Microsoft refers to Product Keys as Serial Numbers. Now, that really helps.