There wasn't any sense of discovery in 3D World though cos the game's limited array of components meant there was never anything really interesting to find in them.
I mean, no one is denying that one game is more exploration heavy. Just that your assertion is, subjectively, wrong to me. I don't think either game is particularly great at having hidden content that's inherently interesting to find, to be honest. It's all an excuse to spend even more time in levels you already like. If anything I might give that to 3D World just based on sheer consistency, since stamps were one of the coolest collectibles I've ever experienced and they were usually hidden.
That being said, Odyssey just by it's nature is usually better at being specifically interesting due to it's exploration. Finding out that jumping off a cliff wasn't an insta-death in Steam Gardens is still one of the coolest moments of this generation for me.