What’s the difference between a Raspberry Pi 4 and the Raspberry Pi Pico?
Updated
The Raspberry Pi Pico is a different device than the Raspberry Pi 4.
The difference between the Raspberry Pi 4 vs. the Raspberry Pi Pico is that the Pico does not have an HDMI port to plug into a monitor, nor USB ports for a keyboard or mouse.
You need to program it for your project and then power it up with a computer or another Raspberry Pi. It is closer to how an Arduino board works than what the Raspberry Pi 4 can do.