Real life ordinary schools teach mathematics, real history, chemistry, biology, physics and etc. In Hogwarts students learn everything about magic. They learn about history of magic, take potion classes, learn about magical creatures and learn about magical spells.
In real life school kids go to school just to take classes and do their homework at home. In Hogwarts students live in school dorms for a whole school year.
In ordinary schools students go to school at age of 6 or 7. Hogwarts accepts students who are 11.
Hogwarts is divided into houses: Gryffindor, Slitherin, Hufflepuff and Ravenclaw. Hogwarts students study for 7 years while in ordinary schools students study or 11 years.