AVR(audio video receiver)- is unit which can be connected to many devices like DVDp,TV,PC & output it to 1 or more devices.It has 5.1/ 7.1amp too.But you need seperate speaker system to drive it.
HTR (home theatre receiver) is same.
HTiB defers which can be all in one-ie DVDP+5.1amp with or without dedicated AVR.