Qudsi means holy, or pure. There are some reports from the Prophet Muhammad where he relates to the people what God has said (says) or did (does), but this information is not part of the Quran.
Scholar define such a report as a hadith qudsi, e.g.: Abu Hurairah reported that Allah’s messenger said: ‘Allah, Mighty and Exalted is He, said: If My servant likes to meet me, I like to meet him, and if he dislikes to meet Me, I dislike to meet him.’
The common factor between hadith qudsi and the Quran is that both contain words from Allah which He revealed to Muhammad. The main points of difference between Quran and hadith qudsi are as follows:
– In the Quran the precise wording is from Allah, while in the hadith qudsi the wording is from the Prophet Muhammad.
– Angel Gabriel brought the Quran to Muhammad, while hadith qudsi may also have been inspired otherwise, such as e.g. in a dream.
– The Quran is inimitable and unique, but not so the hadith qudsi.
– The Quran 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 verse from the Quran. Another point is we cannot recite that a hadith qudsi in prayer.
Source: Taken with some modifications from Ulum Al-Quran: An Introduction to the Sciences of the Qurʼān by Ahmad von DenfferPages: 1 2