Patterns: Form III vs Form VI

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

Form III has an alif after the first radical; Form VI has that alif plus an initial tāʾ.

FeatureForm IIIForm VI
Pastفَاعَلَتَفَاعَلَ
Imperfectيُفَاعِلُيَتَفَاعَلُ
Verbal nounمُفَاعَلَةٌتَفَاعُلٌ

Both can express mutual activity. Nevertheless, their syntax and other lexical meanings are not interchangeable in every sentence. Analyse the form, sentence structure, and context together.