Both Bluetooth and Wi-Fi are used for wireless communication via radio signals!
There is also a difference between WiFi and WiFi , although the biggest difference between Bluetooth and WiFi is that Bluetooth is actually intended for short range devices to exchange information and connect data . Even if the Bluetooth range on modern devices is very far-reaching!
The advantage of bluetooth is
it consumes less power and is ideal for smartphones and wireless peripherals such as headphones, mice, game controllers, ....!
The advantages of Wi-Fi are
it has a higher bandwidth and thus a much faster data transfer rate, additional other devices can be connected to each other and the internet in a network and it has a better range than Bluetooth!