In part of a longer hadith about the compilation of the Qur’an during the time of ‘Uthman ibn ‘Affan, Anas ibn Maalik said:
فَأَرْسَلَ عُثْمَانُ إِلَى حَفْصَةَ أَنْ أَرْسِلِي إِلَيْنَا بِالصُّحُفِ نَنْسَخُهَا فِي الْمَصَاحِفِ ثُمَّ نَرُدُّهَا إِلَيْكِ فَأَرْسَلَتْ بِهَا حَفْصَةُ إِلَى عُثْمَانَ
… ‘Uthman sent a message to Hafsah saying, “Send me the suhuf so that we can copy them over to mushafs, and then we will return them to you.” So Hafsah sent them to ‘Uthman. …
[Saheeh al-Bukhari #4987]
In part of his famous explanation of Saheeh al-Bukhari, al-haafidh ibn Hajr al-‘Asqalaani mentioned the following points about certain differences between the suhuf [loose sheets] of Abu Bakr and the mushaf of ‘Uthman:
الفرق بين الصحف والمصحف أن الصحف الأوراق المجردة التي جمع فيها القرآن في عهد أبي بكر ، وكانت سور مفرقة كل سورة مرتبة بآياتها على حدة لكن لم يرتب بعضها إثر بعض ، فلما نسخت ورتب بعضها إثر بعض صارت مصحفا
The difference between the suhuf [of Abu Bakr] and the mushaf [of ‘Uthman] is that the suhuf were just sheets of paper on which the Qur’an had been compiled during the time of Abu Bakr. Each of the surahs was on its own sheet or sheets of paper with its ayaat arranged in order, but without the surahs picking up one right after the other on the same page. But then when the surahs were copied over and written to follow immediately one after the other, then it became a mushaf.
[Fath al-Bari #4702]
Ibn Hajr goes on to also explain another distinction between the compilation of Abu Bakr and that of ‘Uthman in a later part of the same explanation:
قال ابن التين وغيره : الفرق بين جمع أبي بكر وبين جمع عثمان أن جمع أبي بكر كان لخشية أن يذهب من القرآن شيء بذهاب حملته ، لأنه لم يكن مجموعا في موضع واحد فجمعه في صحائف مرتبا لآيات سوره على ما وقفهم عليه النبي – صلى الله عليه وسلم – وجمع عثمان كان لما كثر الاختلاف في وجوه القرآن حين قرءوه بلغاتهم على اتساع اللغات ، فأدى ذلك ببعضهم إلى تخطئة بعض ، فخشي من تفاقم الأمر في ذلك ، فنسخ تلك الصحف في مصحف واحد مرتبا لسوره كما سيأتي في ” باب تأليف القرآن ” واقتصر من سائر اللغات على لغة قريش محتجا بأنه نزل بلغتهم وإن كان قد وسع في قراءته بلغة غيرهم رفعا للحرج والمشقة في ابتداء الأمر ، فرأى أن الحاجة إلى ذلك انتهت فاقتصر على لغة واحدة ، وكانت لغة قريش أرجح اللغات فاقتصر عليها ، وسيأتي مزيد بيان لذلك بعد باب واحد . ـ
Ibn al-Teen and others have said that the difference between the compilation of Abu Bakr and the compilation of ‘Uthman is that the gathering of Abu Bakr was motivated by fear that some part of the Qur’an might be lost with the loss of those who had memorized the Qur’an. That was because at that time the Qur’an had not been gathered all together in any one place. So he had it gathered all together on sheets of paper with the ayaat of each of its surahs arranged in proper order according to how they had received it from the Prophet.
But the gathering of ‘Uthman was done in a time when there was much differing regarding the Qur’an, such that people would recite it according to their dialect – and this was something permissible – but this led to people thinking that others were reciting incorrectly. So ‘Uthman feared that that would only increase and become more serious. Therefore, he had what had been collected on those sheets of paper transferred over into a single mushaf with the surahs all in order, as will be further explained in the Chapter of “The Writing of the Qur’an”. And ‘Uthman limited the number of dialects to just that of the Quraysh, basing this on the fact that the Qur’an had first been revealed in their dialect even though it had later been permitted to recite it in other dialects in order to remove difficulty and hardship in the early era of Islam. So ‘Uthman saw that the need for that allowance had ceased, and so he limited the mushaf to one single dialect, which was that of the Quraysh. It was the most worthy of the different dialects and thus he limited the mushaf to it. And further details and explanation shall come after the next chapter.
[Fath al-Bari #4702]