The 6QT Air fryer is 1700 watts, and the 8QT Air fryer is only 1500 watts.. Big difference in heating capacity!! Now if we go more in details, Family Size: - The 6qt model is perfect for a small family. - The 8qt model is more suitable for large families. Capacity - The best 6 qt air fryers has a capacity of 2.5 liters. - 8qt model has a capacity of 3.5 liters. Heating: - The 6-cup model has more space and can heat up to 400 degrees Fahrenheit. - The 8-cup model heats up to 425 degrees Fahrenheit and works well for those who like to make food that’s a little bit crisper.