What is the key contrast between عَلَيْهِ and عَلَيْهُ اللَّهَ?

Rules of Hāʾ al-Ḍamīr: Vowels, Ṣilah and Exceptions

• Both have sukūn
• First is ordinary kasrah; second an exceptional ḍammah
• Both have qalqalah
• First is idghām, second ikhfāʾ