Wi-Fi stands for "Wireless Fidelity" and stands for wireless radio transmission.

Wi-Fi stands for "Wireless Fidelity" and stands for wireless radio transmission.
WLAN stands for "Wireless Local Area Network", i.e. a local wireless network (= radio network).
The two terms describe the same ability of the device to connect to a wireless network.
WLAN is built into the vast majority of portable devices, otherwise they cannot be used.

Wi-Fi refers to a radio standard, the term is commonly used abroad, the term WLAN is used in Germany.
You can find more details on Google, simply enter "difference Wi-Fi
WLAN