Metal zamiast OpenGL →

Guy English:

With OpenGL, the current standard for creating graphics, programmers would flip each of these switches and tweak each of these dials individually. Each time they did so, the graphics processor would have to check that the state of the giant machine was still valid.

On the other hand, by using Metal, a programmer can instead define the state they need the machine to be in and then simply apply that state. Rather than tweaking each dial, flipping each switch, and jumping through the correct hoops, the process becomes more like checking off your sushi order from a menu.