Apart from the different labels I can only find one difference: the first stereo edition weighs only 130 g, the second 140 g. All other editions weigh 140 g. The engravings in the dead wax are unchanged!
Which issue do you have?
These are the original editions from 1966:
Mono Labels
Stereo Labels
These are the second editions from 1969:
Mono Labels
Stereo Labels