None of the levels are even close to the same as they were on NES, the layouts have been changed considerably.
Water stages are present and accounted for, too! The bloopers are still just as dangerous.
Hudson Soft was really interested in bridging the gap between Mario's arcade legacy and his home console outing.
Of particular interest, you can't actually stomp on the Mario Bros. Arcade enemies! They must be dealt with using fireballs or from below via blocks.