Ok, hopefully this helps....
Standard Edition is the basic version of the game. It doesn’t include any extras besides the mission gamers get for pre-ordering
Deluxe Edition is for Xbox One, PS4 and Windows PCs. The Desert Cobra Pack includes a sword, outfit, horse, shield and weapon to help gamers get started with the title. Gamers get ability points to unlock power-ups for Bayek early. It has a special naval battle mission too.
Gold Edition unlocks the naval mission and Desert Cobra Pack from the Deluxe Edition. Buyers get access to the game’s season pass in this version.
Steelbook Gold Edition has the Desert Cobra Pack, the exclusive naval mission and the game’s season pass. The game comes wrapped in a decorated SteelBook case.
I bought the Deluxe Edition. I couldn't see spending all that hard earned cash on a season pass that you have no clue what the actual content will be later on down the road.