Final answer:
The first Apple computer to use a Graphical User Interface before the Macintosh was the Apple Lisa, released in 1983, which featured a mouse-driven interface with a significant shift from command-line interfaces.
Step-by-step explanation:
The first Apple computer to use a Graphical User Interface (GUI) that was not a Mac was the Apple Lisa, which was released in 1983. This computer featured a mouse-driven interface with windows, icons, and drop-down menus, signaling a significant shift from the command-line interfaces used at the time. The Apple Lisa pioneered the way for the Macintosh, which was later introduced in 1984, becoming renowned for its user-friendly graphical environment. The development of GUIs was part of the evolution powered by the invention of the microprocessor, and specifically, the Apple Lisa stands out as an important milestone in the personal computing revolution initiated in part by Apple's innovations.