i know the Holy Quran was revealed in seven different Ahruf or dialects but Uthman(ra) burned the different variants and only left one so why is there this difference between Hafs with Qalon & Warsh versions?
Uthman (RA) created several copies of the mushaf to be distributed to different places. They had minor differences between them. This is one of those differences.
Specifically speaking, Imam Ibn Jazari (RA) says that the Mushaf of Madinah and the Mushaf of Sham (Syria) did not have the word هو. The rest had it.
That is why you will find that the reciters of Madinah and the reciters of Syria recited it without the هو, and the rest recited it with the هو.
Does the missing word has any impact on the meaning?
Let's start with the easier thing: The missing word "هو".
This word means in Arabic "he is".
Let's now check the difference in the meaning:
فإن الله الغني الحميد
Can be literally translated:
then indeed, Allah is the Free of need, the Praiseworthy.
While the meaning of the second variation with the additional "هو":
فإن الله هو الغني الحميد
could be translated as:
then indeed, Allah, (only or indeed) He is the Free of need, the Praiseworthy.
Does this add any meaning? "No" (Not really).
Does it make any difference? "Not really".
So from a linguistic perspective one could easily strike the word "هو" and the sentence means the same. In Arabic this addition is used to emphasize and lift any doubt that the speech is about "Allah" and only Allah.
So basically one reading/moshaf adds this confirmation and emphasize while in the other it is regarded as unnecessary.
Before the qur'an was compiled in a Moshaf and later and until today it was and is transmitted orally from teacher to student generation by generation. And this is how Allah intended it to be:
Rather, the Qur'an is distinct verses [preserved] within the breasts of those who have been given knowledge. And none reject Our verses except the wrongdoers.
And the qur'an was transmitted by Sahabah from different Arabic tribes with different slangs and dialects and in cases the sahabah needed to make it easy for the non Arab new Muslims and therefore teaching it by explanation and by synonyms was wide spread (for examples refer to my answer on: What are the readings (qira'at) of Quran?.
So basically if 'Othman didn't make a stop for this we may have a much larger difference!
Let's make an example in English language (and syntax and idioms):
- How are you?
- How are you doing?
- Are you Ok?
- Are you alright?
all these sentences mean the same in English, but they use different words! And now just imagine different qur'an recitations or moshafs with this difference in wording (and this is a rather basic and simple example), wouldn't this lead to more confusion?
- following the recommendation of 'Omar ibn al-Khattab (), after the death of many Sahabah () who were qura'a and hufadh of the qur'an, abu Bakr () ordered the first compilation of a Moshaf by Zayd ibn Thabit () which was kept as a kind of backup at the house of Um al-Mu'minyn Hafsah ().
- In the era of 'Omar many sahabah were sent out to different regions of the Muslim world to teach the qur'an among them 'Abdullah ibn Mas'ud ()who was sent to al-Kufa (and had a huge impact on the Kufi readings), abu Musa al-Ash'ary () who was sent to Basra and abu ad-Darda' () who was sent to a-Shaam etc.
- In the era of 'Othman () a second compilation was necessary as many non-Arabic people accepted Islam and had issues to learn the qur'an and recited it in a rather wrong way, so 'Othman imposed a codex to follow, this way explanative readings and those who used synonyms were basically prohibited after receiving the Moshaf copy in the hands of the new teacher who should teach the people how to recite the qur'an. The words of this moshaf were -in case of disagreement between the members of the committee- taken from the language of the tribe Quraish. Note that there are some reports saying this "revolution" didn't happen without a few discussion. For more information take a look at my answer on: Why is the Hafs reading of the Qur'an so prevalent?.
Why are there missing or added words in some Moshafs?
This is the most difficult question and it could be paraphrased as: where the copies sent by 'Othman to other cities one to one copies of the moshaf al-Imam or not and why? I'm afraid that it can't be answered that easily. But I will try to answer or leave a hint of an answer later