If I’m talking about Wiki pages this is something posted years ago in reference to OH 1.x.
At that time when I posted the above, Scripts were (and are) a way to write a little chunk of callable Rules DSL code in another file. It still uses Rules DSL syntax. So your Rules link applies to both Rules and Scripts.
JSR223 are an alternative to Rules DSL that lets you write your Rules in other programming languages like Jython, JavaScript, or Groovy. Your “Scripting” link is to the docs for this alternative.
And in OH 2, we now have the Experimental Next Gen Rules Engine which will let you write Rules in PaperUI using any of the JSR223 languages (hopefully). But take note of the “experimental” in the name. It’s not yet ready for prime time. Documentation doesn’t really exist yet but I’ve started work on them here: Experimental Next-Gen Rules Engine Documentation 1 of : Introduction