AV vs. Stereo receiver.
A stereo receiver is yer basic two channel (only) receiver that's been around since the 60's that contains a tuner and all amplifiers needed to drive two speakers. Yes, they do still exist.

If two channel stereo is all you want, or will ever expect from it, it can provide the heart of a very fine sounding, yet economical, two channel system.
I just set up for a neighbor a "stereo" system consisting of two small bookshelf speakers, a powered subwoofer, and that aforementioned Sherwood receiver for just under $300 and it sounds like a lot more than she paid for it.
An AV receiver (AVR) is similar except that it also contains 5, 6, or 7 channels and the additional signal processing needed to extract the multi-channel information that movie sound tracks contain.
FWIW, I've got one HT system and three stereo systems in my home even though I have TV's connected to all of them. I simply don't have the room for 5 speakers in all my rooms.