That comparison immediately fails, because the Fatimids originated in Tunisia. They conquered the Maghreb before going east to Egypt, conquering it in 969. (There were several previous attempts, FWIW.) The shift of Fatimid power east from al-Mahdiyyah in Tunisia to Cairo came after it was conquered. So they were a Maghreb power expanding into Egypt, definitely not the other way around.
Couldn't have said it better myself.
they had their origins in Tunisia and conquered North Africa from there. In the early 900s they took Egypt and built Al-Qahira (modern Cairo) and operated from there. Though they still operated from Egypt and had a massive North African Empire
But even then, a Maghrebi empire that conquers Egypt and moves its capital there is still something very different from an Egyptian state that conquers the Maghreb.
What's more; the Fatimids actually lost control of most of North Africa only decades after conquering Egypt.