A receiver is basically an amplifier (stereo or surround) with in-built radio tuner.
You can connect your DVD player to a receivier for sound output.
A DVD player plays DVDs/ CDs and other formats like AVI, MP3 etc. They do not have power amplifier.
So you cannot enjoy home theatre sound without connecting this to a receiver.
But many times DVD players include an in-built amplifier and radio tuner, these are often found in HTiB (Home Theatre in a Box) systems.