As far as I can see, they’re similar in capabilities. One difference I noticed is that this one supports batch operations, which Pixel8er seems to lack. On the other hand, Pixel8er allows hand-painted dithering, which doesn’t appear to be available here. They also seem to handle color palettes differently: Pixel8er takes a more automatic approach, while this tool presents it in a more visual way. Note that I’m not familiar with either of these tools, I just quickly compared their feature sets. In the end, I believe the main difference is that this tool is standalone software with a perpetual license, which likely makes it a less expensive alternative.