Just one simple example. The 'struct' language feature is 1500 LOC in Lisp but only 10 LOC in FORTH (see below.) Are they equivalent? No, the Lisp one has lots of bells and whistles, while the FORTH one is minimalist in the extreme.
If you tried to write the feature-complete Lisp version in FORTH you would probably find it very difficult and unproductive. So you wouldn't do that. And this to me is what FORTH's peculiar brand of efficiency is all about.
If FORTH were a bar the only drink on the menu would be tap water. That bar would be extremely efficient to run.
Lisp: https://github.com/sbcl/sbcl/blob/master/src/code/defstruct.... FORTH: https://github.com/openbios/openfirmware/blob/master/forth/l...