For example,MAX3232, Different suffix ,different footprint. SOC16,TSSOP16,DIP16,Different manufacturers too. Also,same part number with different manufacturer ,it may have different footprint. BC847BT,the footprint in DIODES is SOT523, see datasheet here. however,BC847BT from On Technology ,the footprint is SOT416.see datasheet here. That is why enough BOM information is very important.