عَلِمَتۡ نَفۡسٞ مَّا قَدَّمَتۡ وَأَخَّرَتۡ
(then each) person will know what he has sent forward and kept back.
ٱلَّذِي خَلَقَكَ فَسَوَّىٰكَ فَعَدَلَكَ
who created you and fashioned you and balanced you?
Vowel Difference (harakat) - Change Meaning (general semantic shift)
فَعَدَلَكَ
balanced you
فَعَدَّلَكَ
perfectly proportioned you
The Variant adds a shaddah to the letter dal (changing the verb to Form II), which adds intensity to the action, shifting the meaning from 'balanced you' to 'perfectly proportioned you'.
Bazzi, Duri Abu 'Amr, Hisham, Ibn Dhakwan, Ibn Jummaz, Ibn Wardan, Qalun, Qunbul, Rawh, Ruways, Susi, Warsh
كَلَّا بَلۡ تُكَذِّبُونَ بِٱلدِّينِ
By no means! No! You (still) call the Judgment a lie.
Diacritical Difference (dots) - Change of Person
تُكَذِّبُونَ
You (still) call ... a lie
يُكَذِّبُونَ
they disbelieve
The prefix letter changes from 'Ta' (two dots above) to 'Ya' (two dots below), shifting the subject of the verb from second-person ('You') to third-person ('they').
Ibn Jummaz, Ibn Wardan
ثُمَّ مَآ أَدۡرَىٰكَ مَا يَوۡمُ ٱلدِّينِ
Once again, what will make you know what the Day of Judgment is?
يَوۡمَ لَا تَمۡلِكُ نَفۡسٞ لِّنَفۡسٖ شَيۡـٔٗاۖ وَٱلۡأَمۡرُ يَوۡمَئِذٖ لِّلَّهِ
Vowel Difference (harakat) - Grammatical Case Change
يَوۡمَ
The Day
يَوۡمُ
(It is) a day
The word 'yawm' changes from the accusative case (yawma, acting as an adverb of time 'The day when') to the nominative case (yawmu, acting as a predicate for an implied subject 'It is a day when').
Bazzi, Duri Abu 'Amr, Qunbul, Rawh, Ruways, Susi