Goji berries are, in fact, part of a larger family of berries known as Lycium. It depends on who you talk to as to whether or not one species is as good as another in terms of health benefits. In reality, there is no proof either way until a more thorough analysis of each species is done, including their nutritional content, level of polysaccharides and so on.
The three most common species of Lycium are Lycium barbarum, Lycium chinenses and Lycium europeaum. Even though many botanists apparently tend to group these species under the name Lycium barbarum, they are quite distinct plants. And there are many more species as well, found throughout Europe, Asia and even in the Americas. Common names for goji berries, depending on where you are in the world, are: Gou qi zi, Goji, wolfberry, lycium fruit, bastard jasmine, box thorn, tea tree and matrimony vine.
It has been suggested by some companies that L. barbarum has more polysaccharides than L. chinenses, but studies on L. chinenses do not back this up, and polysaccharides isolated from the L. chinenses have shown promising results in studies on their effect on cancer. Essentially, there is no proof that other varieties of goji berries are any less beneficial than the L. barbarum, although it is the species most commonly sold, in the form of “Himalayan Goji Juice”, as well as in dried berry form.
The main difference between the two popular varieties, is that the L. chinenses variety is a shorter bush and the berries are described by some sources as having a more tart taste.