Difference between sleep() and wait()?

Call on:

•     wait(): Call on an object; current thread must synchronize on the lock object.
•     sleep(): Call on a Thread; always currently executing thread.

Synchronized:

•     wait(): when synchronized multiple threads access same Object one by one.
•     sleep(): when synchronized multiple threads wait for sleep over of sleeping thread.

Hold lock:

•     wait(): release the lock for other objects to have chance to execute.
•     sleep(): keep lock for at least t times if timeout specified or somebody interrupt.

Wake-up condition:

•     wait(): until call notify(), notifyAll() from object
•     sleep(): until at least time expire or call interrupt().

Usage:

•     sleep(): for time-synchronization and;
•     wait(): for multi-thread-synchronization.