I had some difficulty finding out the content of the Deluxe, so I probably clicked too much around, the icons are the same for the Deluxe and Summer edition for me? Probably because I have Morrowind and Skyrim on Steam but not Oblivion.

It's weird it's so hard to find the details on the "includes nine expansions" on Steam. Normally there are descriptions. But it only says for instance "Fighter's Stronghold Expansion" with no information on it that I can see?

PS: One of the cool things about original Oblivion, is that it allows you to play the Nehrim total conversion. Although I can see it has huge problems on Steam. But I played it when the English version came out, and IMO it is as good as the original game.