Great question! Ativan (lorazepam) and Xanax (alprazolam) are both benzodiazepines used mainly for anxiety, but they have some important differences.  Buy Ativan Online Without a Prescription Ativan vs. Xanax Comparison Feature Ativan (Lorazepam) Xanax (Alprazolam) Onset of action 20–30 minutes 15–30 minutes (sligh