Among mostly subtle changes for Apple's 13-inch MacBooks, the graphics silicon stands out as the one distinct difference between the new and old models. So, what, graphically speaking, has changed exactly?

A lot. Apple was clearly making a point when it updated the 13-inch MacBook Pro and then followed with the white MacBook update this week: Nvidia graphics chips matter more than Intel processors. At least, in the case of these two models they do.

So, what do users get when they opt for a newer MacBook or MacBook Pro? A pretty significant jump in graphics performance, according to reviews and experts.

The bottom line is that the newer Nvidia GeForce 320M chipset has 48 processing cores versus 16 cores in the older GeForce 9400M chipset that was used in the previous generation of MacBooks. (And note that in the case of the 320M, it is a chipset, not a standalone graphics processor. Typically, Intel makes the chipset that accompanies the main processor and Nvidia attaches a discrete graphics processor to this. But in this case, Nvidia supplies the chipset containing the graphics silicon.)

The white Apple MacBook, seen here from the front and side, was updated this week with faster Nvidia graphics silicon, like the 13-inch MacBook Pro before it.