جَاءَ زَيْدٌ الْعَالِمُ: al-ʿālimu is an adjective describing Zayd.
جَاءَ زَيْدٌ نَفْسُهُ: nafsuhu is emphasis confirming the very individual.
جَاءَ زَيْدٌ أَخُوكَ: akhūka may be parsed as apposition or explicative apposition depending on the syntactic intent.
These teaching comparisons demonstrate distinct follower functions.