Although these plants look similar there are a number of ways to tell them apart. Firstly even though they both have large flat leaves the Peperomia Polybotrya has leaves shaped like raindrops with a distinct point at the tip. Where as the Pilea has round leaves large coins. Secondly when the Peperomia flowers it puts out beautiful tendril like things that grow upwards and towards light sources. A Pilea on the other hand will put out small delicate flowers.