Hi MICHAEL B, Are you absolutely sure your Sony isn't a +/-R? The DVD+R and DVD-R are competing formats much like the old VHS and Beta formats in video tapes. Today most drives are Hybrid and handle both formats. They are usually labeled DVD+/-R I ju...
Here's an article discussing the different recording media
As for companies, Sony, Canon, JVC, and Panasonic are the biggest players in the field. In terms of media, the common digital formats are miniDV tape, Digital-8 tape, hard drive, memory card, DVD, and a few professional formats including, but not lim...