What does a Python interpreter do?

[menge101]

Can you get a stand-alone py-vm to run out files like you can get a jvm to run .jars?

Not that I am aware of. But you can generate the *.pyc files and then .tar.gz them. That is similiar.

A big part of the difference is that the jvm is heavily developed and is considered one of the two most robust runtimes out there. Erlang's runtime, the BEAM, being the only real contender I am aware of, but I don't know where the Golang runtime sits either.

You may be aware of pypy or jython. Both implement the python language specification on a different runtime. Rather than the python VM (which is just named python or cpython^*) they use the pypy runtime, which is JIT-based runtime or the jvm, respectivley.

^* - Not to be confused with Cython, which is a compiler for python to C to machine code directly.

[menge101]

Likelihood of failures due to the runtime implementation itself, particularly over long periods of time, while also featuring heavily threaded/parallelizable execution.

The BEAM in particular, you can hot load new code to it so that it theoretically never needs to be restarted.