The Qur'an was Nazala, and the Torah & Gospel were Anzala.
What's the Difference?
In Surah Aal 'Imraan, verse 3,
Although the English translation reflects no difference in the original words that were used to convey the meaning of 'sent down', a look at the Arabic will show us that the form nazzala نزَّلَwas used in reference to the Qur'an while the form anzala أَنْزَلَwas used in reference to the Torah and the Gospel.نَزَّلَ عَلَيْكَ الْكِتَابَ بِالْحَقِّ مُصَدِّقاً لِّمَا بَيْنَ يَدَيْهِ وَأَنزَلَ التَّوْرَاةَ وَالإِنجِيلَIt is He Who has sent down the Book (the Quran) to you (Muhammad SAW) with truth, confirming what came before it. And he sent down the Torah and the Gospel.
The reason for this goes back to the manner of revelation – the Qur'an was gradually revealed in a number of stages that spanned the 23 years of the Prophet Muhammad's (sallaa Allaahu 'alayhi wa sallam) Prophethood, as is reflected by the form nazzalawhich indicates repetition and graduality, while the Torah and the Gospel were revealed to the Prophets Musa (Moses) and 'Eesa (Jesus) at one time, as reflected by the form anzala.
This difference is more beautifully sealed when we look at the first verse of Surah al-Qadr,
In this verse, Allaah has used the verb anzala – which does not reflect graduality – to describe the revelation of the Qur'an, although He previously used nazzala! The reason for this is clear when the word is considered in it's context, as is explained by Ibn 'Abbas and others,إِنَّا أَنزَلْنَاهُ فِي لَيْلَةِ الْقَدْرِVerily! We have sent it (this Quran) down in the night of Al-Qadr (Decree)
"Allah sent the Qur'an down all at one time from the Preserved Tablet to the House of Might (Bayt al-'Izzah), which is in the heaven of this world. Then it came down in parts to the Messenger of Allah based upon the incidents that occurred over a period of twenty-three years.''Thus, it is clear that this verse is referring to Allaah sending the Qur'an down at one time to Bayt al-'Izzah on Laylat al-Qadr, and not to its gradual revelation to the Prophet; a concept so precisely and beautifully conveyed just through knowing the meaning of the forms used in the original Arabic.