'61Reiussue (also the same as the '62Reissue or SG62, except the 62 had "reissue" pickups and the 61 has 57Classics). The classics have enamel wire coating vs formvar on the reissue. Tone is very similar.
You can see, they're the reverse of US coins where the Presidents head gets smaller and smaller as the President gets closer to the present time. Here with the SG's, the older SG models must have been much smaller... just look at the pictures!
The Standards have modern neck joint, the 61/62 is the older neck joint.
Inlays are small blocks on the Standard, traps on the 61/62
Switch location
The Standards have either SuperHumbucking or 490 pickups (which are not the same as modern 490s which IMO sound better), the 61/62 have reissue or 57 Classic pickups
The Standards have the post-Harmonics TOM bridge (Schaller TOM), while the 61/62 have the ABR-1 TOM bridge.
Metal key tuners on the Standards, green plastic keystone on the 61/62
Standards have engraved nameplate that says SG, 61/62 are plain
Standards have rather square body bevels, 61/62 have correct deep bevels
Standards have neck pickup against the neck while 61/62 have proper spacer between neck pickup and neck
Finally, look at the control locations - the Standard has what I call the angled pot layout, while the 61/62 has the straight pot layout.
I never noticed the switch location on the Standard. Looks way to far back and close to the knobs to be practical. I think I like the larger bridge/neck pickup spacing though.