>From way back at the bike shop we asked the same thing, what was the difference?
For a while, middle 70's it appeared to be the box was the difference.
The G.S. had possibly rougher texture at the sand finish section and the machining of the cylinder was probably done at a faster feed rate.
Weight and function, no difference.
Later other minor changes would appear, the Nuovo Record got some of the attributes from the Super Record, the barrel nut getting the internal conical machining and the lower brackets sometimes arrived in alloy. Do note that early Super Record posts shared the barrel nut design for quite a while, only later getting the "conical" change. And if one ordered a less popular sized post, it would quite possibly be from earlier stock / design, they did not worry too much about model year back then.
The first seat posts we saw with the limit line marked were with Complete bikes from Raleigh, quite a while before loose parts arrived with them.
Torrance Ca USA