Both the iOS and Android versions of Pocket Edition have the same gameplay, which is akin to that of the Classic game mode, with the following differences: World is finite as in Classic version but there isn't infinite water at world corners. The terrain generation is similar to that of Alpha's. It lacks many biomes, generated structures. With the survival update tools were added. These were: swords, shovels, pickaxes, axes, and shears. In game items differ slightly to the Classic version. The notable differences being the addition of Quartz and Nether blocks. Clouds are in Pocket Edition as of 0.6.0. They are 2D like the clouds on PC in "Fast" graphics setting. As of 0.6.0 the sky in Pocket Edition only has clouds and a lush blue color. Sun, moon, and stars will be added in more updates. It lacks many of the settings the Classic version has.
Pocket Edition has physics for sand, gravel, and primed TNT. Online (LAN) mode only allows 5 players to be on a single server. Internet support is in development. Crafting using the MATTIS system.
The world size is 256x256 blocks.
The Nether is not present, but it is replaced by the Nether Reactor. The Reactor is planned to eventually be replaced. Roses are not present, but are replaced by Cyan Flowers, alias Blue Roses. However, in the hot bar, it is named "Rose". Also, the red dye is obtained by burning red mushrooms in a furnace. All of the included blocks (as of version 0.5.0) are as follows-
Cobblestone, Moss Stone, Stone...