The main difference between the Roo Double and Roo Single is the size of the hammock. The Roo Double is 10 ft long, and can hold up to 500 lb. We recommend the Roo Double if you plan to camp overnight in your hammock, or if you will frequently be hammocking with two people. The Roo Single is 8 ft long and holds up to 400 lb. At only 10 oz, we recommend the Roo Single for those wanting a lightweight hammock they can take anywhere.