What is the reason of this differences in the three expressions in Surat Al-Kahf 79 - 82?

Allah says in Surat Al-Kahf in aya 79: > أَمَّا السَّفِينَةُ فَكَانَتْ لِمَسَاكِينَ يَعْمَلُونَ فِي الْبَحْرِ > **فَأَرَدتُّ** أَنْ أَعِيبَهَا وَكَانَ وَرَاءَهُم مَّلِكٌ يَأْخُذُ كُلَّ سَفِينَةٍ غَصْبًا > > As for the ship, it belonged to poor people working at sea. So **I > intended** to cause defect in it as there was after them a king who > seized every [good] ship by force then in the next aya : > وَأَمَّا الْغُلَامُ فَكَانَ أَبَوَاهُ مُؤْمِنَيْنِ **فَخَشِينَا** > أَن يُرْهِقَهُمَا طُغْيَانًا وَكُفْرًا، **فَأَرَدْنَا** أَن > يُبْدِلَهُمَا رَبُّهُمَا خَيْرًا مِّنْهُ زَكَاةً وَأَقْرَبَ رُحْمًا > > And as for the boy, his parents were believers, and **we feared** that he > would overburden them by transgression and disbelief, So **we > intended** that their Lord should substitute for them one better than > him in purity and nearer to mercy then: > وَأَمَّا الْجِدَارُ فَكَانَ لِغُلَامَيْنِ يَتِيمَيْنِ فِي الْمَدِينَةِ > وَكَانَ تَحْتَهُ كَنزٌ لَّهُمَا وَكَانَ أَبُوهُمَا صَالِحًا > **فَأَرَادَ رَبُّكَ** أَن يَبْلُغَا أَشُدَّهُمَا وَيَسْتَخْرِجَا كَنزَهُمَا رَحْمَةً مِّن رَّبِّكَ ۚ وَمَا فَعَلْتُهُ عَنْ أَمْرِي ۚ > ذَٰلِكَ تَأْوِيلُ مَا لَمْ تَسْطِع عَّلَيْهِ صَبْرًا > > And as for the wall, it belonged to two orphan boys in the city, and > there was beneath it a treasure for them, and their father had been > righteous. So **your Lord intended** that they reach maturity and > extract their treasure, as a mercy from your Lord. And I did it not of > my own accord. That is the interpretation of that about which you > could not have patience. What is the reason of this difference in the three stories ?! Knowing that all this knowledge from God and his appreciation