Hi drumkeys , the reason because you hear the patch different between the patch mode and perform mode is only that in the last one is affected by the common effect parameters to the specific perform here you only can select one effect and have the reverb and chorus for all 16 parts , but if you like very much one patch efx setting you can assign all the parts with this by putting in the efx window in output assign mode
PAT and choosing the part number that is related to your patch, also can be hear different for the parameters of the part (coarse tune, controllers ,tempo,etc)
i hope this help. huge