Clonazepam and Xanax are both benzodiazepines.It is used to treat anxiety, but they differ primarily in speed of onset and duration . Xanax is generally considered stronger on a milligram to milligram basis .It acts faster, making it better for immediate panic attacks.Clonazepam is not necessarily weaker But it is longer acting and It stays in the body much longer 22 to 54 hours than Xanax. Because Xanax stays in our body for 6 to 25 hours .