Super Mario World for the NES is a bootleg port of the video game of the same name by Hummer Team, a Taiwanese pirate game developer. It is their attempt at porting a game that was originally for the SNES and making it fit the technical constraints of the NES. The result is what can be expected from a bootleg video game. Levels from the original game are missing, the physics are messed up, and gameplay mechanics such as warps were not implemented. The result is a rather linear game that doesn't play like the original Super Mario World very much.
Darkman425 here tackles this rather well-known NES bootleg and beats it as fast as possible.
Watch this run being played back on a real console.