The main difference is that Pyston-Lite is a CPython plugin, while MyPyC is an AOT compiler that emits CPython extension modules.

But if you're asking about performance and use cases, there are a lot of Python compilers and alternative implementations out there now!

Not just MyPyC, but also Nuitka, Shedskin (not sure if still in development), GraalPython, PyPy, Cinder, Pyjion, IronPython (not sure if still in development), and even Stackless Python (yes it's still in develoment). Not to mention Cython and, for specific numerical tasks, Numba.

I think Microsoft also recently announced a CPython JIT extension that's analogous to Pyston-Lite.

A benchmark or comprehensive comparison suite would be pretty cool, but I'm not aware of one. Personally I think CPython plugins are the most user-friendly option, because they require the fewest changes in your deployment setup and runtime environment. PyPy isn't that bad but isn't perfect either. Whereas ahead-of-time compilation is a pretty big change from the usual Python developer workflow and might not be easy to convince a team to adopt it.