Is 5G and 6G the same WiFi 5/6G or GHz?

No. Sometimes Wi-Fi or wireless LAN's get marked with "5 G" or "6 G" but this is short for GHz, referring to the frequency range or the band. The "G" in mobile cellular (phone) networks is short for Generation. Any overlap/inclusions in the frequencies is thus coincidental. It's a mistake if something suggests a Wi-Fi network is cellular "5G" or such. The same goes for 2G and 2.4 GHz networks.