https://techcrunch.com/2020/10/19/raspberry-pi-foundation-launches-compute-module-4-for-industrial-users/

The Raspberry Pi Foundation is launching a new product today — the Compute Module 4. If you’ve been keeping an eye on the Raspberry Pi releases, you know that the flagship Raspberry Pi 4 was released in June 2019. The Compute Module 4 features the same processor, but packed in a compute module for industrial use cases.

A traditional Raspberry Pi is a single-board computer with a ton of ports sticking out. Compute Modules are somewhat different. Those system-on-module variants are more compact single-board computers without any traditional port.