Sure, and I'm glad you asked. The 47-piece tileset is for terrains that have a lot of symmetry, allowing for someone to rotate and flip the tiles, saving artist time and file size in the process. The 256-piece tileset allows me to create asymmetrical designs, and even designs that overlap tiles. Here's an example of a few of the forest tiles I use. Notice how certain connecting edges have trees that are intended to overlap into the next tile:
Now let me show you the template beneath it so you can see why I made the artistic choices I made:
As you can see, I wanted the trees to trail off a certain way depending on the surrounding tiles. Here's a bit of my tileset being used on my current WIP:
As you can see, it flows relatively smoothly and doesn't look overly tiled.
Hopefully this clears up my choices a bit more! If not, I could break it down even more, if that would help.
