There are three main different types of antennas: Directional-, omnidirectional- and sector antennas. The main difference is the beamwidth.
There are essentially two different frequency bands in which a WiFi network can work with. The 2.4 GHz and the 5 GHz frequency band. The 2.4 Ghz frequency band according to IEEE802.11b/g/n is still the current standard. The 5 GHz frequency band with the IEEE802.11a/n/ac standards is a bit more susceptible to interference, but offers much more channels than the 2.4 GHz frequency band and is therefore used more and more often. In addition, extremely high data rates are possible here