tl;dr version

- Blood purity isn't important like it is in UK. All students are educated thoroughly about the no-maj world.

- There isn't as much emphasis on House differences. Many different personalities span inside the same Ilvermorny House.

- Ilvermorny students are more used to seeing magical creatures around.

- Dormitories are separated by year and gender, not by house.

- Ilvermorny has over 1000 students, while Hogwarts has about quarter of that. Because of this, you're less likely to know everyone at the school, and its harder to stand out.

- Students don't get their wands until they're at Ilvermorny.

- All NEWT students have to take Charms, Transfiguration, DADA and Potions.

- There is an elementary level school, Ardeevin, that American witches and wizards between 5-11 attend. It's a day school, and teaches basic skills not magic, but includes no-maj studies and creature care on the syllabus.

- Students can learn wandless magic in later years.

- There are no Prefects / Head Girl & Boy.

- There is a Student Council and two Student Council Presidents. They are more organisers of the school events and there to help students. They do not give out punishments.

- There is more than one Professor per subject.

- The house colours are not part of the Ilvermorny uniform, they can just wear a house badge if they want to.

- Ilvermorny uses Wampus cats for security/guarding, and Pukwudgies for maintenance/ basic operations of the school.