وَيُعَبَّرُ عَنْ هَذَا التَّرْكِيبِ فِي الِاصْطِلَاحِ بِأَنَّهُ جَارٌّ وَمَجْرُورٌ.
Translation: This construction is termed a preposition with its genitive complement.
وَيُعَبَّرُ عَنْهُ فِي الِاصْطِلَاحِ بِأَنَّهُ مُضَافٌ وَمُضَافٌ إِلَيْهِ.
Translation: The other construction is termed mudāf and mudāf ilayh.
In مَرَرْتُ بِزَيْدٍ, bi- is a preposition governing Zaydin. In غُلَامُ زَيْدٍ, ghulāmu is mudāf and Zaydin is mudāf ilayh. Both have a genitive element, but their constructions differ.