Earlier quoted context omitted.
It substantially comes down to the amount of language practice those students have had over the years, starting from listening to large amounts of varied material (from conversations/books read aloud) as young children, and then from reading a wide variety of material. The kids who read, and read, and read (especially those who have someone discuss with them the meaning and structure of what they are reading, hearing…
>the ability to “memorize” (i.e. learn) I don't disagree with any of what you're saying. But piecing little bits and pieces of things together is seen as a higher-level cognitive trait in most of the cognitive literature, quite distinct as a learning concept from memorization.
Students’ skill at specifically remembering lists of atomized trivia (what people often mean when they say “aptitude for memorization”) is not as important, though this is also a trainable skill for anyone who really wants to do it.
Similarly, between the kids who play sports or do other physical activities all the time and have some amount of expert coaching and the kids who only play sports in PE class, there is probably something like a 10x difference in cumulative quantity/quality of past practice. Which ends up making it seem that some students are “athletic” and others aren’t.
And similarly for music, electronics, carpentry, abstract mathematics, cooking, shooter games, or whatever other skills you look at.