Sheikh ibn Baaz (May Allaah have mercy upon him) was asked:
Is the Witr prayer different than the night
prayer in terms of it’s timing, the duaa that is made in the two prayers, as
well as the number of units of prayer that is made in it?
His Reply was:
The Witr prayer is part of the night prayer. It
is from the Sunnah and something that is recommended to do. It is the
way in which the night prayer should be completed or finished. The
Witr prayer is one unit of prayer, in which you end the night prayer.
This is done either at the end of the night, in the middle of the night or even
in the beginning of the night after the Isha prayer.