Marrakech is quite different if you compare it to Fes. For example, in Fes, the city has more up and downs so there are more tiny narrow streets. Marrakech does have many tiny streets, however Fes has more (the streets in Marrakech are bigger and flatter compared to Fes). In Marrakech, there are many more scooters and motorcycles in the streets, and in Fes, the majority is donkeys. Marrakech has a way bigger town square than Fes (the town square in Fes is very tiny and is next to the blue gate (Bab Boujloud)). Also, Marrakech has many more beggars and people who are more aggressive.
Now for the similarities. Interestingly, Marrakech and Fes both have a wall around the medina because medina means the old, walled part of a North African town. It is also interesting that in both Marrakech and Fes, the trash pickup uses donkeys!!! They both had a tannery and there were people selling leather in both cities (I also saw a lot of people selling jewelry such as necklaces, bracelets, and earrings).
Those are some similarities and differences between Fes and Marrakech. I personally liked Fes more, because Marrakech is more Westernized and has lost a bit of its culture. I am sure that there are way more similarities and differences that I did not mention.