Are they 2 different brands of media.Ps2's have funny lazers and they will except some type of media's and not others.
THE DVD+RW IS MAXELL AND THE DVD+R IS VERBETIM. AS IT SO HAPPENS THE +R DECIDED TO WORK TONIGHT, LAST NIGHT IT DIDN'T READ. JUST FINISHED REDOING THE R+S ON RW GO FIGURE LOL
I would use a good Ritek G04 media with your ps2 as the ps2 lazers seem to like them.If you writer does multi format use the - media these will work great.Try to stick with one brand of media as the older your ps2 becomes the more tempermental your ps2 lazer will become.If you want to preserve your lazer for as long as possible find a good media that your ps2 will read well and stick with it.