The Keurig K-Mini is the updated, slimmer version of the K15 and operates with the same simple brewing system: There are no brew sizes or special functions.
Instead, you add water to the K-Mini's 12 oz water reservoir, press Brew, and the machine brews every drop of water you added.
What's changed from the K15 to the K-Mini?
Note that the High Altitude setting isn't a button you press. Instead, Keurig says you activate the setting by inserting the pod into the machine and puncturing it by pressing down with your hand before sealing the pod compartment (as opposed to sealing the compartment in order to puncture the lid).
Keurig also makes the K-Mini Plus, which offers everything in the base K-Mini with a few extra features that you can read about in our K-Mini Plus Review.