This is the only one that has "Compact" in the name.
That's because the K-Compact is the smallest Keurig coffee maker with a removable water reservoir.
The K-Mini and K-Mini Plus are smaller (and slimmer at just 4.8" wide) but have 12 oz reservoirs that need to be refilled before each use.
Like the K-Minis, the K-Slim is just 4.8" wide, but it also has a larger 46 oz water reservoir. Unfortunately, the K-Slim's reservoir is non-removable and can be hard to access if you don't have over-brewer clearance.
The K-Compact gives you a multi-cup reservoir (36 oz, 4-6 cups) with a removable design that makes refilling easy, and it weighs just 6.9 lbs when empty and measures just 8.2" wide.