Jerry,
In my opinion, RARE is when you are dealing with a chip that less than 4 are known. That is rare!!!
Super rare is when you have a chip that only two are known - ie, Joe & Willie's Mint from Carson City, Nevada. This is a rare chip!!

You get the idea - number known will establish the use of the term - rare.
The problem is many dealers & collectors throw this term around very loosely.
What happens is everything is rare - so nothing is rare. Sad - Best, Jim