v86 also recompiles machine code to web assembly. The main difference is that v86 is a hobby project (of which I'm the original author, by the way), with much fewer contributors and no (known) commercial users, and is much less sophisticated than this project. On the other hand, v86 is open source, so you could make it sophisticated if you wanted to :-)

I'm not sure what exactly cheerps is used for; v86 is mostly used to demo operating systems (mostly hobby and vintage). We recently got SerenityOS to run: http://copy.sh/v86/?profile=serenity