The canonical Lisps still widely used today are Common Lisp, Scheme and Emacs Lisp. They all belong in the same family, and syntax / semantics are close. Porting code from Scheme to Common Lisp can be a lot easier than going from Python 2 to Python 3.

Clojure is something else entirely which is why a lot of people don't consider it a Lisp.

> Honest question: how do you communicate between two Lisp processes on two different machines?

If you want to use built-in object serialization, there is print and read.