Repetition of stories in the Quran with different wording
Question

What is the wisdom behind the repetition of stories in the Quran?
Praise be to Allah.The repetition of stories and their wording in the Holy Quran, but in different contexts and synonymous wording, is one of the obvious characteristics of Quranic story-telling, as one story may be repeated in more than one surah, and each time it is told in a different context and different style. Thus the story is repeated with new phrases which give different shades of meaning and offer new lessons, in various eloquent styles. Hence the scholars and commentators regarded this variation in wording and phrases as one of the aspects of eloquence, and they stated that one of the objectives of the Quranic stories is that one incident may be mentioned in different contexts. They even wrote books devoted to this technique, one of which is the book al-Muqtanis fi Fawa’id Tikrar al-Qasas, by Badr al-Din ibn Jama‘ah, which was mentioned by al-Suyuti in al-Itqan (2/184).
Al-Zarkashi (may Allah have mercy on him) said: Presenting the same idea with different techniques and styles is quite clearly a sign of eloquence."(Al-Burhan fi ‘Ulum al-Quran 3/26).
If we want to count the benefits that this variation in presentation may add to the beauty of the Quran, we would list many such benefits. We will mention some of them below:
1.
Adding some details that were not mentioned in other contexts. The example mentioned in the question is one type of these benefits. The verses in Surat al-Hijr add a more specific description of the material from which Adam (peace be upon him) was created, which is the fact that he was created from dry clay, made from black mud moulded into shape, which was not mentioned in the verses of Surat al-A‘raf which refer to the same idea.
2.
Confirming the challenge that the Quran brought to the polytheist Arabs, to produce something like what is in the Quran. This variation in presenting one idea exposed their inability to produce anything like it in any style and in any words they could come up with.
3.
Enlivening the story so that the reader will not get bored with it. That is because a new variation in presentation of the story makes one more attentive and more inclined to listen, and it keeps the reader engaged and interested when reading this holy text. This is also one of the greatest objectives. Thus the eloquent person will find himself inclined to listen to it, because of the natural human inclination to move between a variety of things, each of which gives its own pleasure.
4.
Presenting one topic in an amazing way when it is presented in different styles. The polytheists at the time of the Prophet (blessings and peace of Allah be upon him) were amazed at how often these stories were repeated, in a different style every time, even though the topic was the same. Thus Allah, may He be glorified, showed them that what they were amazed at was produced by One Whose power is infinite and Whose words cannot be counted.
5.
Creating harmony between the topic and the context in which the story is presented. Sometimes the context requires highlighting some aspect of the story in the discussion that takes place therein, that did not need to be highlighted in another context in which the same story was mentioned. This reason is one of the bases of the eloquence of the Quran and its miraculous nature. It is discussed in more detail in some books of Tafsir.
You can read about these benefits and others in the book al-Burhan fi ‘Ulum al-Quran (3/26-29).
Dr. Fadl Hasan ‘Abbas (may Allah have mercy on him) says: The storytelling method in the Holy Quran is a brilliant and miraculous method, as a story may be mentioned in many surahs. Although some surahs may mention a single detail from the story, other scenes and incidents are mentioned in other surahs in which the same story is mentioned, whether there are many events in the story or few. Thus in each surah you will find a detail of the story that you do not find elsewhere, and each surah mentions some detail that is appropriate to the topic and context of that surah. Thus the story is mentioned in the surahs in a particular place in each surah that is appropriate for it."(Al-Qasas al-Qurani  81).
And Allah knows best.