The full version and upgrade version are the same. Since Adobe no longer sells CS5 beware you might have purchased a forgery. Some dealers still have inventory left but if it does not work correctly call Adobe and see if serial number is valid.
Thank you. I thought I read that if I don't have an older version installed I would need to enter my serial key for the earlier version. Is this not the case?
And thanks for the warning. I had considered that risk, but the person I purchased from had a good rep on Ebay and I paid with Paypal so I figured I could easily dispute the purchase if it was fake.
Yes, to get upgrade pricing from Adobe you have to enter the qualifying s/n. Not sure how this would work with a private seller as Adobe does not know whether you paid upgrade or full price. It might be built into the serial number.
The serial number is definitely the method used by Adobe to distinguish full versions from upgrades.
Has been for several years.