You don't find star coins in 3D world. You find stars. The experience of finding stars in 3D World is just like finding stars/suns/moons in the other 3D Mario games. 3D World starts out as "flagpole Mario" and gradually transitions to "starfinder Mario".
You're right, star coins is 3d Land, 3d World was green stars. But does it matter? Mechanically they're identical. 3 of them in each level, they work exactly the same as star coins, so changing them so they're no longer a "coin" isn't really relevant.
They're not "just like finding stars/suns/moons" because unlike 64/sunshine/galaxy they don't end the level when collected. They're closer to Odyssey, but with 3 in each level they're actually identical to the star coins from nsmb and 3d land in everything but appearance.Last edited by Barkley - on 12 September 2019