launch(To activate an application program (especially on the Macintosh) from the operating system's user interface); initialize(To prepare a disk or computer for use); start(To start or reset a computer by turning the power on, by pressing a reset button on the computer case, or by issuing a software command to restart)
Start(The Windows home screen and replacement for the Start menu, which includes apps, websites, and other info that users can specify and customize); startup(The process of starting or resetting a computer. When first turned on (cold boot) or reset (warm boot), the computer runs the software that loads and starts the computer's operating system, which prepares it for use)