there isn't much difference except for cost. PVC is by far a better product though. ABS doesn't insulate the noise as much as pvc and is more likely to warp and bow than pvc. personally being a plumber I prefer PVC because of these reasons and for your small project abs just wouldn't be worth it to me because you don't save enough on cost to worry about it. The only other factor would be if you have a color preference if your piping is visable.. hope this answered your question
Thank for the answer, my system is already all on PVC but I've heard so much controversy about-it, many said that my overcome with a rise of bacteria etc, whos right, but in the far end it could be useful to take the black ABS for the color, its easier to hide and !