How should ṣāliḥ and aṣlaḥ be distinguished?

Divine Guidance and Misguidance, and the Debate over What Is Best

• Ṣāliḥ means more beneficial and aṣlaḥ less beneficial
• Both always mean creation
• One refers only to the Hereafter and the other only to worldly life
• Ṣāliḥ is fitting or beneficial; aṣlaḥ is comparatively more fitting or beneficial