As nouns the difference between pen and pin is that pen is an enclosed area used to contain domesticated animals, especially sheep or cattle or pen can be a tool, originally made from a feather but now usually a small tubular instrument, containing ink used to write or make marks or pen can be a female swan or pen can be penalty while pin is a small device, made (usually) of drawn-out steel wire with one end sharpened and the...

The main difference between Pen and Pin is that the Pen is a writing implement and Pin is a fastening device; device used for fastening objects or material together; often has two components: a long body and sharp tip made of steel, or occasionally copper or brass, and a larger head often made of plastic.