MMP is for associates and direct family. MMF is for friends. Both have limited availability but MMF availability is generally better but with a smaller discount. You need the employee to give you a sheet to fill out either way. If you have any friend that works for Marriott, they can get you the MMF discount. If you cause any trouble during the stay however, you jeopardize their access to this privileged rate and even their job.

This is a “perk” Marriott gives out instead of fairly compensating its employees.