What is a parked thread in Linux kernel?

What is a parked thread in the context of Linux kernel? I mean a thread that is in TASK_PARKED state? How this state differs from TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE? From which state a thread can be woken faster? Generally, and in particular case if used for waiting: kthread_parkme / kthread_unpark instead of [s]wait_event_... / [s]wake_up_...]? I know that waitqueues support multiple waiters, but I am interested only in a single sleeper/waker pair.