What is the difference between a Wi-Fi extender and an external antenna

What is Wi-Fi Extender ?
A Wi-Fi extender, also known as a Wi-Fi repeater or range extender, is a device that helps increase the coverage area of a Wi-Fi network by amplifying the existing Wi-Fi signal from a router or access point and rebroadcasting it. Here's how it works and some key points about Wi-Fi extenders:

Signal Amplification: A Wi-Fi extender receives the Wi-Fi signal from the primary router or access point and then amplifies it before rebroadcasting it. This amplified signal can reach areas of a home, office, or other space where the original Wi-Fi signal might be weak or nonexistent.

Extended Coverage: The primary purpose of a Wi-Fi extender is to extend the coverage area of a Wi-Fi network, allowing devices farther away from the main router to connect to the network with a stronger signal. This is particularly useful in larger homes, offices, or spaces with multiple floors where the Wi-Fi signal might not reach all areas effectively.