While the terms "antler" and "horn" are sometimes used interchangeably, they refer to different structures.
* Antlers are bony structures found on the heads of male deer (and sometimes females) that are shed and regrown annually. They are covered in velvet during growth and are used for fighting and display.
* Horns, on the other hand, are permanent structures made of keratin (the same material as human hair and nails) that are found on animals like cows, goats, and sheep.
So, while a deer's horn might look like a horn, it is actually an antler.