The soft Senseo®-like pod has a diameter of 55mm, which is the largest on the market. In this pod, the coffee is not tamped so no big pressure is required to pass through it. With soft pods, you will serve a rather light coffee.
The E.S.E. pod (Easy Serving Espresso) has a diameter of 44mm, it is a stiff pod as the coffee inside is tamped. Why? Because it is able to stand a 16-bar pressure required for a quality espresso. Thus, as its name indicates, this pod is used to prepare an espresso or a ristretto, which are intense and strong coffees.