This sounds to me more like a difference in compressibility than a difference in memory capacity. If you know what an airplane is and have a mental model of it

This sounds to me more like a difference in compressibility than a difference in memory capacity. If you know what an airplane is and have a mental model of it in your mind, you need only store the differences between this particular airplane and the general model. On the other hand if you have never seen an airplane before, most of your efforts are going to be focused on storing this weird tube shape with little things poking out the sides. Yeah if you count capacity by the number of files you can store, you have increased capacity, but that's a weird way, at least in my opinion, to look at it.