What is the chief contrast between “al-kutubu maḥfūẓatun” and “yaḥfaẓu al-amīnu al-kutuba”?

Supplementary Practice 11: Report, Objection-Reply and Instruction

• The former necessarily expresses reversal restriction
• The latter is a prohibition rather than a report
• The former emphasizes state, the latter the custodian’s action
• The former is always future and the latter always past