Ṭalab al-taṣawwur seeks identification. The speaker already accepts some relation or event but does not know which member or feature should be assigned to it.
أَعَلِيٌّ مُسَافِرٌ أَمْ خَالِدٌ؟
Is ʿAlī travelling or Khālid?
The fact that someone is travelling is presupposed; what is sought is which individual. The answer identifies ʿAlī or Khālid.
Ṭalab al-taṣdīq instead asks whether the relation or event obtains at all.
أَسَافَرَ عَلِيٌّ؟
Did ʿAlī travel?
Here yes or no is an appropriate response. The distinction turns on whether the missing knowledge is an identity or the truth of a claim.