DVD-A is recorded to a potentially much higher standard and resolution,with the ability to go to 24 bit/96kHz or 24/192kHz,whereas DVD-V with surround(5.1)sound will be recorded at a somewhat lower bitrate.
Having said that,there are some atrocious DVD-A offerings around currently,released from major manufacturer's back catalogues,and some DVD-V recordings,especially live concerst,which are far superior.
That's about it in a nutshell,but it does make choosing a good example of each a bit of a lottery,although you can search the forums for advice on each.
Another aspect is whether or not you want/enjoy the video side of things,in which case the DVD-V route is the choice.