Valium and Xanax are both benzodiazepines. It works by enhancing the effects of GABA in the brain to reduce anxiety. The primary differences lie in their speed of onset and duration: Xanax is faster acting and shorter lived making it better for panic attacks, while Valium acts longer and is better for ongoing anxiety. Valium begins to work within 30 to 60 minutes. It provides immediate relief from anxiety symptoms such as excessive worry, restlessness .