Default PE is a double sized resolution of the default textures (32×32 instead of 16×16) in Minecraft PE. Why? Because Minecraft PE is a great game with great texture. Everything in Minecraft PE looks quite nice, but maybe just a little bit pixelated. Some people just need Minecraft to look a bit smoother. As a result, all textures are more detailed which make them look better. Everything just look better, not different.
All credit goes to SteelBrother, VolyFNAP, and SLembas