The only one I can recognise as a conventional SG is the middle one.
Did they have an era where they made them without scratchplates?
The white one is a rare 24 fret model which was made with no pickguard. All sg1500's were also made with no pickguards. Some rare models and one-offs came out of the factory without them too. Some of them are SBG's, not SG's... which have a thinner body width and a slightly smaller neck taper. The red mettalic one has a factory trem unit on it.
Sucks trying to get parts for them though because Yamaha does not stock parts for them, even though they are re-releasing them in the United States in a few months for the first time in years. Wish I could find a a rubber O-ring to install an elevated pickguard on the sunburst model. Oh well...