> The toybox build produces a multicall binary, a "swiss-army-knife" program that acts differently depending on the name it was called by (cp, mv, cat...). Installing toybox adds symlinks for each command name to the $PATH.
> The special "toybox" command treats its first argument as the command to run. With no arguments, it lists available commands. This allows you to use toybox without installing it, and is the only command that can have an arbitrary suffix (hence "toybox-armv5l").
Edit: found it elsewhere in the thread. It's rewritten because they didn't like GPL for religious reasons. (Busybox is a completely separate binary from the rest of the system so there is no reason not to ship GPL-licensed software that I can see, but yeah if you've been bitten by making a closed source work derived from GPL once, I guess you don't want to try it again and Android has a lot of vendors with closed source components.)
This is one of the reasons why Google Android, and probably many others, are using Toybox for their userland. Because it's distributed under a BSD license.