How are cymbalta and effexor (venlafaxine) xr different?

Different compounds: Cymbalta and Effexor (venlafaxine) XR are different chemical compounds which are both used to treat depression and anxiety disorders; however, they share a similar "mechanism of action", in that both are serotonin and norepinephrine reuptake inhibitors (snri's). Cymbalta is also used in the management of fibromyalgia and (in europe, at least) urinary incontinence. Their side-effect profiles are also different.