This is the second Mario platformer for the GameBoy. The graphics are significantly improved, it looks quite a bit like Super Mario World on the SNES, although it is obviously in greyscale and much lower resolution. It also has a world map where you select levels like the SNES game too.
Overall the game is very short, and very easy. I think the level design is a real step down from the first one. I managed to get all of the retro achievements for it.