Grammar stream: just a marketing buzzword? Any different from being in the top set?

[ParentOfOne]

I have noticed that some state, non-selective secondary schools now have "grammar streams".
They do not admit any pupils based on a test and regardless of distance.
They still admit mostly based on distance. But admitted students sit a test and the best ones are put in a "grammar stream".

They make a big song and dance about it, but my question is.... is this any different from dividing students into different sets or streams but without shouting "grammar stream" from the rooftops? (I understand sets can vary by subject while a stream applies to all subjects, right?)

This is an article from 5 years ago about this trend: https://schoolsweek.co.uk/91656-2/

At this school https://www.barnsley-academy.org/education-with-character/the-grammar-stream "They will be taught a more challenging and in-depth curriculum from Year 7 onwards, as well as having access to a programme of extracurricular opportunities". The structure in most schools (academies) of this group seems the same

It seems that this group has taken over a number of schools which weren't doing well. So is this just a marketing buzzword to signal that, under new management, they are much better?

Or is there some merit to it? In which case, what would be the difference from the typical school that divides students into sets or streams?

@PinkLemonJuice The "grammar stream" in question simply means choosing the best students among those who have already been admitted (mostly by distance).
It does not mean choosing the best students, regardless of distance.

So I don't think it can be too different from a school which simply divides pupils by sets.

Note that here "best" simply means the students who get the best scores at their 11+ or similar exams - exams on which I have my doubts, but that's a whole different conversation