The cookers are very similar, in that they are able to grill, air crisp, bake, roast, dehydrate and dehydrate food. The Ninja Foodi Smart XL 6-in-1 Grill has a sixth function -- broiling. It also has a larger grill surface than the 5-in-1. The XL can cook six steaks at once, while the Ninja Foodi 5-in-1 Grill can cook four. The XL 6-in-1 has a 4-quart cooking pot for roasting, while the 5-in-1 has a 6-quart cooking pot for roasting. Some versions of the 5-in-1 Grill (like ours) have an integrated thermometer probe, while others do not. The XL 6-in-1 Grill comes standard with an integrated smart thermometer to continuously monitor meat temperatures. Both Foodi grills have a 4-quart air fryer.