EMH is a benefit of the onsite hotels. Permits early entry to either DL or DCA every day of your stay at any of the three onsite hotels. Which park has EMH depends on the day of the week.
MM is a benefit of a 3 day (or more) hopper. I permits one (1) early entry day per ticket at DL only on specific days of the week.
The super thread linked above will give you more specific information