Scheme is smaller, has more static and less interactive philosophy. CL has most things you need straight out of the box. It's more like operating system than programming language. Exactly what Emacs wants to be.
elisp is more like CL than it is like Scheme; RMS was aware of CL when he was working on emacs, but was suspicious of some of its new features (like lexical binding).
Emacs' Elisp it's pretty close to Common Lisp, any CL user can learn Elisp in days (and the opposite it's true too). There's even a port of PAIP exercises into Elisp:
Interesting, why not a scheme? Is it because the popularity in the industry? I don't know much about Emacs or lisps and looking to understand better