DVD,DVD-R, DVD-ram?

[k4kyv]

What is the difference between regular DVD recording and DVD-ram?

My friend has a pair of fancy new DVD player-recorders.  He made a copy of a DVD that I have, that I purchased from Amazon.com.  The quality of my disc is pretty poor, but the copy he made is substantially better, with a sharper image and less "tileing".  He says that the new recorder has some kind of "processing" that removes some of the junk and corrects some of the errors present on the original.  The quality of a disc copied off a VHS tape onto DVD-R is also better than the original.

The disc he copied from mine was in DVD-ram format.  He then made a copy of the DVD-ram disc onto regular DVD-R, which still shows better image quality than my original. But his DVD-ram won't play on my DVD player.  The screen menu indicates "no disc".  I tried running his DVD-ram copy through my computer, but all I can get is an error message that the disc is "not formatted".

His machine will play either regular DVD and DVD-ram.  He does not own a computer.

I had assumed that DVD-ram would be the same format as streaming video off the internet or a DVD data disc, but my computer's CD/DVD drive (which is read-only) won't recognise it.  I know that DVD's can be used to store computer data, just like a CD, and that a data CD is not the same format as an audio CD.

But what exactly is DVD-ram and why won't it play on my computer drive?

[Pete, WA2CWA]

Google dvd-ram and it brings up a ton of info on what it is, what it does, etc.