A system for selectively delivering different beverages having different foam levels by injection of a fluid under pressure into a capsule that contains a beverage-forming substance. The capsules include a chamber containing the substance and a beverage dispensing structure adapted to retain a certain extraction pressure in the chamber before allowing the beverage to flow out of the capsule. The system is characterized in that first and second capsules are provided for selective use in the system, with the first capsule having a first beverage dispensing structure configured and positioned therein to retain a first extraction pressure in the capsule, prior to the complete delivery of the beverage, and the second capsule having a second beverage dispensing structure configured and positioned therein to retain a second extraction pressure in the capsule, prior to the complete delivery of the beverage. The first extraction pressure is higher than the second extraction pressure so that a greater amount of foam is created upon delivery of the beverage from the first capsule as compared to that created by the second capsule. This allows a user of the system to select a cartridge that produces a beverage with the desired foam content.