Complex sentence: Unlike Second LIfe, users cannot buy and sell products in Lively, and the hairstyles, clothing and furniture are not programmable but are limited a catalog of pre-designed selections.
Split into simpler sentences: Unlike Second LIfe, the Lively users cannot buy and sell products. Since there is no user-generated content on Lively, items such as hairstyles, clothing and furniture are limited a catalog of pre-designed selections.