CS5.1 vs. CS5 Extended
What is the difference between CS5.1 and CS5 Extended?
I bought a CS5 Extended CD, but recently downloaded a CS5.1 directly from Adobe.
Are both the same product?
Yes, they are the same. This version moniker was only used to distinguish between the then new Creative Cloud and the normal suitzes and to reflect the relevant technical changes in the licensing system.