The Qur'an can be defined as follows:
-The speech of Allah, sent down upon the last Prophet Muhammad,
through the Angel Gabriel, in its precise meaning and precise wording,
transmitted to us by numerous persons (tawatur), both verbally and in writing.
- Inimitable and unique, protected by God from corruption.
There is agreement among most Muslim scholars that the contents of the sunna are also from Allah. Hence they have described it as also being the result of some form of inspiration.
In the Qur'an the precise wording is from Allah, while in the hadith qudsi the wording is given by the Prophet Muhammad.
The Qur'an has been brought to Muhammad only by the Angel Gabriel, while hadith qudsi may also have been inspired otherwise, such as e.g. in a dream.
The Qur'an is inimitable and unique, but not so the hadith qudsi.
The Qur'an has been transmitted by numerous persons, (tawatur) but the hadith and hadith qudsi often only by a few or even one individual. There are hadith qudsi which are sahih, but also others hasan, or even da'if, while there is no doubt at all about any aya from the Qur'an.
It was not recited or written as a part of quran.