See https://en.wikipedia.org/wiki/The_Two_Cultures
When I was homeschooling my son I got him between 2-3 grades above grade level at math. He was so good at mental arithmetic that I had to improve my skills to keep up with him. On the other hand I was not able to get him to do algebra at all and he did not master it in high school although he did OK with geometry.
From my viewpoint it was really puzzling, almost like he had some kind of psychological resistance or mental block to the whole idea of algebra.