Better reefs and turtles south, more to do and cheaper flights north.
They are on the same sea and about 270 km apart, and the difference is essentially development.

Marsa Alam is newer, quieter and closer to the good reefs. The house reefs are better — many hotels have coral directly off the beach — turtles are routine at Abu Dabbab, and the southern dive sites and marine parks start here rather than being a day's travel away. It is also emptier, with less to do outside the hotel.
Hurghada has the volume: more flights and cheaper ones, more hotels at every price, a real town with markets and restaurants, and by far the widest choice of excursions. Cairo and Luxor are both reachable as day trips, which from Marsa Alam is much harder.


Hurghada has the volume: more flights and cheaper ones, more hotels at every price, a real town with markets and restaurants, and by far the widest choice of excursions.
The simple rule: if the holiday is mostly about what is underwater, base in Marsa Alam. If it is a mixed holiday with pyramids, temples, desert and a town to walk around in the evening, base in Hurghada and take the southern reefs as a long day trip.

