The main differences are dimensions, total volume air and water, and housing capability. The Biopod EdenĀ and Terra are intended to house terrestrial animals only, while the Aqua 2 and Grand can house both terrestrial and aquatic/semi-aquatic animals. As far as plants go, the Eden and Aqua are great for small plants, but larger plants can only be grown in the Aqua 2 and the Grand.