What distinguishes hāʾ in فَهُوَ and فَأُمُّهُ?

Al-Qāriʿah and Az-Zalzalah — Comparative Tajwīd Practice

• First belongs to an independent pronoun; second is an attached pronoun hāʾ
• Both are hāʾ of pause
• Both cause obligatory madd
• Both are tāʾ marbūṭah