OTA vs. OTT

The often used abbreviations can be confusing. Think of OTA (Over The Air) as using a TV antenna, where the signal comes into your antenna, literally over the air from satellite or huge broadcast antenna at a TV or radio station, vs. on a cable.
Think of  OTT (Over The Top) as directly accessing the internet via a physical cable (such as the one that goes into your modem/router LINK). WiFi also gets its input from that cable. It refers to audio, video, and other media transmitted via the Internet without cable or direct-broadcast satellite television systems controlling content. No TV tuner or receiver is necessary.

OTT devices which support streaming include Chromecast, Apple TV, Roku, and FireTV, etc. OTT services include video on demand services like YouTube, Netflix, Amazon, Hulu, Sky Go, BBC iPlayer, etc.

Bottom line, OTA uses the air outside of your house to receive signals and OTT uses cables outside of your house to receive signals. They both use cables from the wall to devices inside the house.