What's the difference between a pestle and an iron bar?

An iron pestle is an iron bar used to pound rice or clothes.

Iron bars, also known as lifting iron bars, are a relatively large form of stick performance. At the bottom of it is a low table made of superior hardwood, which is more than two feet high, six feet long and about five feet wide. There are 10 foot long lifting rods on each side of the table top. The center of the wooden desk is an iron core, which is fixed under the desktop and divided into three or two sockets. The performer stands on the pedal of the socket, his body is flush with the T-shaped iron, and he is tightly wrapped and fixed with white cloth from bottom to waist. An iron bar with three sockets can stand three performers, and an iron bar with two sockets can stand two performers. Among these performers, those with higher skills play the leading role, while those with lower skills are on the lower side of the iron frame. The average iron bar is four meters high, and it can reach five meters when it is lifted and walked around. However, it is high but not dangerous. Only when a performer stands tall can he be seen by a distant audience.

Iron pestle and iron bar are the same thing, and they are called differently because of their different usages.