Why is the use of the dots for differentiating the letters in Warsh, Hafs, and other narrations of the Qur’ân different? Is it because there were many ways of writing the Arabic alphabet at the time of the Messenger (peace be upon him)? How come there are different vowelings for words in different narrations of the Qur’ân?
Dots were not in use at the era of the Companions. They were only known from the era of the Successors. The purpose of developing the dots was to avoid mistakes being made while reading the Qur’ân. Systems of dotting letters were the results of personal efforts and they took different configurations.
The differences you see between Warsh and Hafs with respect to dotting the letters is because dotting systems of eastern Arabs and western Arabs are different. It has nothing whatsoever to do with the era of our Prophet (peace be upon him) when dots were not used at all. The system employed for writing down the Arabic alphabet in a manuscript generally corresponded to the conventions of people in the country where the manuscript was produced.
The voweling of the text does not deviate from how it was during the era of `Uthmân. The voweling in the narration of Warsh will be in accordance with that narrations particular reading. The same can be said about other narrations. Voweling corresponds to the specific narration for reciting the Qur’ân.
This took place because there were differences in the voweling in the copies originally sent by `Uthmân to the different countries. It was `Uthmân’s intent to preserve all the recitation styles that were revealed to the Prophet (peace be upon him). However, all manuscripts in existence comply with the vowelings approved by the Companions who received the different manners of recitation directly from the Prophet (peace be upon him).
Source: Islam Today
-- Al Arabiya Digital