The term ‘partition’ is both a verb and a noun. When you partition a hard drive, you physically create separate sections on the hard drive; each of these sections is called a partition. A partition defines a specific area of a hard drive. It has a beginning point and an ending point; the difference between these two points equals the total amount of space the partition defines. A hard drive can have multiple partitions. Once the partitions are created, they can be used independently of each other.
When Apple’s Disk Utility creates partitions, it adds a file system to each partition so your Mac can read data from and write data to the partition. Once you use Disk Utility to partition your hard drive, the resulting partitions are more correctly referred to as ‘volumes.’