The drop factor differs (# of gtts/mL). A set that delivers large drops per mL (10-20 gtt/ml, usually 15) is called macrodrip set. One uses smaller gtts (60gtt/mL) is called microdrip. Usually the macrodrip set is used if the IV rate is to infuse > 100ml/hr. Vice versa, Microdrip < 100ml/hr volume.
Here is the drip rate calculation:
Volume (mL)/ time (min) x drip factor= gtt/min
ranges 30-100 gtt/min.