system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why is a hard drive so much bigger in comparison to a SD Cards or USB stick, even though the storage space is the same?
gpt
Because a mechanical hard drive needs to fit its spinning platters, optical reader assembly, and controller circuitry into its chassis. 

Flash memory devices like USB sticks and SD cards have no moving parts, storing their data directly on a chip. Therefore, they can be much smaller.