The terms selective and superselective are applied to state Grammars.
Super selective only admits purely in exam result with no reference to other things such as address and no catchment area. Applicants are ranked according to exam result and places given out until no places left.
Selective is a school where you have to pass the exam, but once you're above the pass mark, places are awarded according to to their criteria such as distance.
Typically a full grammar area like Kent or Bucks takes the top 25-30% and the schools are selective. Super selectives with zero catchment criteria but purely exam based like QE Barnet might take the top 5% of ability.
Independent schools cannot be ranked like this. Those who can afford to apply are limited.
In terms of selection, few independents if any will have the 2800 applicants for about 100 places that the Barnet state grammars have.
Therefore, it's easier to get an offer, in terms of applicants per place. Being in he top few to earn a sizeable bursary (only given if achieving at top level and meeting the means testing criteria) will be much harder to achieve.
It is often the case that those who get places in super selective state schools also get bursary and/or scholarship offers. Scholarship offers are not means tested and tend to be small amounts, and alone won't allow most famikies to afford the fees.
So, the majority of places at somewhere like Trinity go to full fee payers. They need to, in order to fund it. Most of them wouldn't get into the super selective, but some would.
It is always difficult to tell by looking at applicants per place as lots of kids sit several schools but can only take one place. Even very selective schools (Independnet) have to significantly over offer in order to fill. Geography in particular leads to even the most popular schools getting rejections from some of those they make offers to.
Is the Q more about pecking order if schools?