Your searches make sense.
Media player - used to play back music files stored on a computer, NAS, etc. JRivers, Foobar, WindowsMP, etc
These will not be plugged into your receiver but are software for PC based playback.
Components - devices used for online streaming services (Tidal, Spotify, etc.).
These will plug into your receiver. Examples:
https://www.crutchfield.com/g_105800/Music-Servers.html?tp=71839