Certainly real Goji is different genera from L. barbarum/chinensis - but in terms of the product sold most of time you'll never know for sure, but even the common Wolfberries are very good.
"Goji polysaccharides were proved to be exceptional source of the essential sugars like Rhamnose, Xylose, Glucose, Mannose, Arabinose, and Galactose". Quted text from Tim O'Shea http://www.gojiberries.us Commercial website-do not know how/where he got his information.