These buttons can be programmed for different types of coffee such as an espresso, doppio or ristretto. This means once you have mastered a particular style of coffee, you can get it the same every time.
With an integrated milk frother, the machine can automatically produce frothed milk for use in cappuccinos and other drinks.
With one press of a button you can create a cappuccino.
A higher number of grind settings gives you more flexibility when choosing the fineness of your ground coffee. The particle size is important as a grind which is too coarse can produce weak tasting espresso, whereas a grind which is too fine can lead to a bitter taste.
With a double boiler or heat exchanger system, you can brew and steam milk at the same time. This has an advantage over single boiler machines where you have to wait between brewing and steaming for the temperature to adjust.
With a pre-infusion function you get a low pressure of water before it ramps up to around 9 bar of pressure. This gently expands the grinds to get a smooth extraction and to help prevent channeling in the cake.