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.
some htib refers to speakers + avr - example onkyo htibs
Some times dvdp is also integrated, like in lg, philips and samsungs.
What is the basic difference between an AVR and a HTR? Do they actually differ from one another?

These are loose terms and I think you are asking HTR not HTIB so HTR is Home theatre receiver which is same as modern AVR Audio Video Reciver.
Still you get 2 channel AVR too.

May I understand reason of asking this?So that we can guide...
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