What main syntactic difference separates the Form III and Form VI examples?

Seven Semantic Functions of Form VI (Tafāʿul): Reciprocity, Multiplicity, Pretence, Response, Equivalence, and Independent Uses

• Both are passive
• ʿAmr is an object in the first but coordinated with the subject in the second
• ʿAmr is accusative in both
• Zayd is the object in both