Source: Sharh 'Aqeedat il-Waasitiyyah, tape no. 18/4,9
Shaykh Saalih al-Fawzaan (hafidhahullaah) explains the similarities/differences between hadeeth Qudsi and hadeeth Nabawee; and between hadeeth Qudsi and the Qur'aan:
"Hadeeth Qudsi: the wording and the meaning is from Allaah, 'azza wa jal
Hadeeth Nabawee: the wording is from the Messenger (sallAllaahu 'alayhi wa sallam) and the meaning is from Allaah, 'azza wa jal
Both Hadeeth Qudsi and the Qur'aan are the speech of Allaah.
But:
The Qur'aan is mutawaatir.
Hadeeth Qudsi may not be mutawaatir; it could be aahaad, it could be dha'eef (weak), it could be hasan...
One worships (Allaah) by reciting the Qur'aan, in prayer and other than that.
Hadeeth Qudsi is not recited (melodiously) as an act of worship (as the Qur'aan is)."