Completely different beasts. Busybox is a tight, lightweight implementation of [a subset of] the Posix toolchain. This thing - also tight and lightweight - is a collection of commands primarily geared towards manipulation of file names and contents. Highly un-unixy (more like "do all sorts of things and do them well") but with clear, straightforward, non-arcane syntacs.

I had a pile of somewhat complex text transformations I needed to perform, and was getting headaches just contemplating the hodge-podge of cat and grep and find and awk and sed and regex and stackoverflow and kilometers of pipes I would be getting into, not being much of a wizard with such things, so went looking for something a bit less daunting. Found this, and within in an hour had a working script which I am fairly certain I will also be able to read and understand a year from now.