Distinguishing between Salatul-Witr and Qiyamul-Layl

One issue that needs clarification, and concerns which mistakes are made, is differentiating between Salatul-Witr and Qiyamul-Layl (the Night Prayer). There are ten key distinctions between them:

• Witr is a restricted voluntary prayer, while Salatul-Layl or Qiyamul-Layl is an unrestricted voluntary prayer.
• Witr is not the best restricted voluntary act according to the most correct point of view of the Madhhab (school of thought), whereas Salatul-Layl is the best unrestricted voluntary act.
• The time of Witr begins after ‘Isha for everyone. The time for Salatul-Layl begins after sunset (Maghrib).

It is considered Saheeh according to Abu Dawoud and others – on the authority of Anas (Radia-Allaahu ‘anhu) – that the verse, “They used to sleep but little by night” [Surat Adh-Dhariyaat (51:17)], was revealed concerning the prayer between Maghrib and ‘Isha.

• The best of Witr is at the end of the night – i.e., the time of Sahar (pre-dawn). We will clarify this further. The best Qiyamul-Layl is during the third part after midnight – i.e., when you divide the night into two halves, then divide the second half into three, the best Salatul-Layl will be that which is offered during the first third (of the second half).

For example, the night – according to the Madhhab – is from sunset to dawn – and (we assume that) the duration between the two is twelve hours, and if the sun sets at 6:00pm, then the second half begins at 12 midnight. The six hours from 12 midnight to 6:00am are to be divided into three, and the first third, i.e., from 12 midnight to 2am – is the time when Qiyam is better than Qiyam at the end of the night.

When the Prophet (Salla-Allaahu ‘alayhi wa sallam) mentioned the Qiyam of Prophet Dawoud [David (‘Alayhis-salaam)], he mentioned that he (‘Alayhis-Salaam) used to sleep half of the night, then pray a sixth of it, and sleep the remaining sixth. This is also the Prophetic Sunnah; he (Salla-Allaahu ‘alayhi wa sallam) used to sleep during the last sixth of the night. In a Hadeeth from ‘Aishah (Radia-Allaahu ‘anha) in the Saheeh, she mentioned that the Prophet (Salla-Allaahu ‘alayhi wa sallam) never passed the last hours of the night except sleeping. [Al-Bukhaari no. 1133]

• It is Mustahab (recommended) to restrict the number of Witr, while there is no restriction for the number of Rak’ahs of Qiyamul-Layl.
• Witr is offered in odd numbers only, while Qiyamul-Layl can either be odd or even. Witr is either performed as one, three, five, seven, nine, or eleven Rak’ahs, and this is Mustahab (recommended), while Qiyamul-Layl can be both odd and even. It can be Qiyamul-Layl even if someone prays eight Rak’ahs between Maghrib and ‘Isha. In this case, it is not permissible for him to offer Witr before the ‘Isha prayer. The prayer which he offers at this time is Qiyamul-Layl – and he should offer them as even numbers.If he does not pray anything else except it during the night (for Qiyam), then it will be counted as Qiyam for that night, but if he offers Witr as an odd number, then it can also be considered as Qiyamul-Layl even if it is odd – i.e., if he offers it after ‘Isha, and he intends Witr, and he offers an odd number of Rak’ah of one, three,  five, etc. – in this case, he will have offered Qiyamul-Layl and he will have offered Witr too – because every Witr is Qiyamul-Layl but not every Qiyamul-Layl is Witr.
• Qunoot is Mustahab (recommended) in Witr, which is the Du’aa after Ruku’ in the last Rak’ah. There is no Qunoot in Qiyamul-Layl.
• Witr is followed by Dhikr, which is the phrase “Subhaanal-Malikil-Quddoos” three times. Qiyamul-Layl is not followed by Dhikr unless it is being performed as Witr, i.e. if one intends Witr when he offers Qiyamul-Layl, then it should be followed by Dhikr that is recited after Witr.
• Witr can be made up (i.e., made Qadha of). It is recommended for the one who misses it, to make up for it – this is Mustahab according to the Hanbalis. (However,) Salatul-Layl cannot be made up. He, who misses his Witr, should make it up in the same manner as he would normally do, according to the Hanbali school. (For instance,) if someone intended to pray five Rak’ahs of Witr but he fell asleep, he can make it up by praying those five Rak’ahs during the daytime at Duhaa time. Ibn Taymiyyah (Rahimahullaah) said that he should make up for it as an even number of Rak’ah, i.e. he should make up five Raka’ah as six Rak’ahs. And this is the stronger opinion.
• It is Sunnah to offer Witr regularly, whereas it is disliked to offer Qiyamul-Layl regularly (according to the Hanbali Madhhab). This view is mentioned by several of their scholars, including Ibn Muflih, the elder in Al-Furu’ and Ibn Muflih, the grandson in Al-Mubdi’- contrary to what Al-Hajjawi stated in Al-Iqna’, where he interpreted their intent as a dislike of offering the Qiyam the entire night.
  It appears that the Hanbali opinion is a general dislike of offering Qiyamul-Layl regularly, even if only part of the night is prayed.
  However, the preferred view is that offering the night prayer regularly is not disliked, as many verses and Ahadeeth encourage night prayer and highlight its noble status.

Source:
Ten differences between Witr prayer and Qiyamul-Layl by Shaikh Salih Al-Esaimi (Hafidhahullaah)