Qiyaam’ means ‘standing’ and ‘Qiyaam al-Layl’ means ‘standing in night.’ In the Islamic terminology, both terms refer to 'the voluntary night prayer, whose time extends from after ‘Ishaa’ (evening) prayer until dawn.’ Qiyaam al-Layl is also known as Tahajjud.
A widespread misconception is that Tahajjud is a different night prayer than Qiyaam. The true is that there is only one voluntary night prayer known by different names.