Different color of 16-bit water (this could probably actually be done without too much trouble, but I'm just guessing), layers that go in front of water.

Different form of textured background.

Different color of 16-bit water, maybe ambient lighting but it's hard to tell.

Multiple tilesets, background looks a bit odd but I'm not sure.

CTF arrow in treasure hunt... the palette looks weird but I don't feel like testing it.

More fancy effects added to sugar rush, plus utter disregard for how JJ2 works.

Multiple tilesets, and we can see that the level uses some sort of "primary" palette. One wonders how well this would work in 8-bit...

Multiple/new tilesets, different centerpoint of textured background, new game mode.