STB Emu codes and IPTV Xtream codes are used to access IPTV (Internet Protocol Television) services, which allow users to stream live TV channels and on-demand content over the internet. STB Emu (Set-Top Box Emulator) codes are used to configure the STB Emu app, while IPTV Xtream codes are used to access Xtream codes-based IPTV services.