There are some major differences that may look small details at first. The width of the plates is one of them. Small, medium and large versions are available depending on hair length. Medium is the most common as it can be used for both short and long hair.
As for its material, aluminum, Teflon or painted plates are not as recommended as ceramic plates.
Temperature and its adjustability is another key factor. Different hair types require different temperature. If instead of the advertised 200-220°C a device can only heat up to 100-120°C, it will not succeed on a high rate.