What is Instant Hotspot on the iPhone?

How is Instant Hotspot different from Personal Hotspot?

iOS Personal Hotspot

Instant Hotspot is an Apple Continuity feature designed to seamlessly connect Apple devices to your iPhone's Personal Hotspot. The Personal Hotspot provides a Wi-Fi signal to nearby devices using the cellular data connection.

Instant Hotspot works automatically on iOS 13 or later with any devices signed into iCloud with the same Apple ID. Connections are made when needed without entering the Personal Hotspot password.

Instant Hotspot uses Bluetooth to connect nearby devices and Wi-Fi to transfer data.