The time between two user-defined events. Usually the first event is triggered right after the users credentials have been entered (session login event), and the second event is triggered when all user specific initialization has finished (processes started or settled).
Startup time
The time that elapses from the OS is started, that is after any BIOS initialization, until a user configurable event is triggered. The event will usually mark the end of the boot process.
Detailed startup
A detailed breakdown of the resources consumed by all processes during operating system start up, including the relative time when the processes started.