Memory and disk storage both refer to internal storage space in a computer. Each is used for a different purpose.
The term “memory” usually means RAM (Random Access Memory); RAM is hardware that allows the computer to efficiently perform more than one task at a time (i.e., multi-task).
The terms “disk space” and “storage” usually refer to hard drive storage. Hard drive storage is typically used for long-term storage of various types of files. Higher capacity hard drives can store larger amounts and sizes of files, such as videos, music, pictures, and documents.
“Virtual memory” is hard disk space that has been designated to act like RAM. It assists the computer with multi-tasking when there is not a sufficient amount of RAM for the tasks.
Computers also contain a small amount of ROM (Read-Only Memory) containing permanent or semi-permanent (firmware) instructions for checking hardware and starting up the computer. On a PC, this is called the BIOS.