Violet,
We tend to ignore the EPR gauges on 321`s except during the take off to check that the correct thrust has been achieved. On approach, if using manual thrust, just scan down to the N1 gauges and the numbers are very similar to the 320.
Otherwise there is little difference. The 321 is a bit more slippery when descent planning but feels a bit more stable in all axis.
Other than that there is no problem flying the two types.