Just had a look. It looks partly smoke and mirrors to me.
Main: Maths 5 English 5 Science 4 (total 14)
Grammar: maths 4 English 4 Science 6 (total 14)
Main: Humanities 5 (total 5)
Grammar: History 2 Geog 2 RE 1 (total 5)
Main: Sport & Art & Music & DT & PSHE (total 7)
Grammar: Sport, Art & Music & DT & PSHE (total 7)
So far not much difference.
Main: Languages 3, Performing arts 1
Grammar: Spanish 2, Latin/Classical civilisation 2
So there you have it.
Grammar gets slightly less maths/English and slightly more science.
Grammar doesn't get to do any performing arts but gets to do some Latin.
Most of the way they have laid it out on the web page is advertising in my view. For grammar they have listed the science subjects separately, but the mainstream kids will still do them, even if called 'science'. Similarly for the 'humanities'.
But I'm only judging from the outside so it's not really fair.
I really don't like the idea of a test though.
And I strongly prefer setting to early streaming too.