Hello Norm,
good to have you aboard!
It's actually quite complicated and it will need some trial and error to sort things out.
The first RvG series originate from Japan. These so called JRvG's were issued in the mini LP format. Later on the US (and the rest of the world) got the "domestic" RvG series. Since a lot of people complained about the narrow stereo spread of many of the JRvG's Cuscuna asked RvG to redo some of them for the US market. Later on the JRvG's and the RvG's use the same masters (you can tell this from the remastering date which is given on both issues). The 1500 series from Japan you are refering to are 24 bit remastered in Japan and sound really good imo. There's some complaining about the loud'ish compression on these. Most people on this board (and elswhere) think the older Japanese TOCJ series sound best (the one with the LP number after the TOCJ prefix). These are hard to get nowadays but you should try to locate some to hear for yourself.
The TOCJ-70xx series use the same US RvG remasters.
Hope this helps........
Please keep on asking if you need more info.
Cheers,
Reinier