DLNA video streaming? Need to understand it better

Hey there guys, I really don't where should I post it so I hope this doesn't break any rules.

I keep reading about DLNA but I've always used samba share with me media players on my house.
With samba I know the device read the files on my computer and there's no difference except speed comparing a playback from a samba share and a usb connection.

Now if you use DLNA if I understand it correctly the device will not render the file, the computer will do the job and pass that along. It would be in a very rough comparission a virtual desktop or VNC for videos.
The video goes ready to the device and it shows display the image.

Is that correct? How does DLNA works?
The wikipedia on it talks nothing about the technical side and this really interest me.