erm its really just a format difference, there are no capacity differences as far as i know of, its like when video tapes first came out there were Betamax, vhs and some others, well now writable DVD's have come out there are different formats. Some dvd players/recorders will record and play on both, some will only record and play one type. a modern computer DVD burner will read and write both but some dvd players (from home entertainment systems) will only read one type. so make sure you use the right type for your needs.
well MOST home dvd players DVD+R is the preferred format but 50% of them will play DVD-R, but as matt said most modern dvd drives play anyting including DVD+R,DVD-R and DVD-RAM!
Actually DVD-R is more compatible with standalone players as the technology is older and quite a few of the older players will not recognize DVD+R. CDR-Info did a study and DVD-R was 96.1% compatible with standalone players while DVD+R was only 87.6%. You can view the article here. DVD+R has the technological edge as it is a newer technologiy and they were able to add a few things into the spec like lossless linking across the entire disc, built in defect management and addressing during recording. Here's a link for most of the differences in the two formats.
