The easiest way to describe the differences between the 'young' and the 'old' Goldberg variations as played by Glenn Gould are to look at the runtimes. As I get older I find myself liking the ones played by the older Gould better.
If you haven't heard it, Hilary Hahn's Chaconne is also slow compared to a lot of other interpretations, and for me has a lot of the same impact (makes me cry, basically, but stimulates a huge range of emotions in a very short time) as the later Gould recording. https://www.youtube.com/watch?v=QqA3qQMKueA
