Arduino Leonardo model differences
At the end of the day the Leonardo is just a chip (ATMega32U4) on a board with a voltage regulator, a couple of LEDs and USB socket / shield headers. There's not much else to it.

Different revisions may change some of the support components - maybe a component went EOL and they needed to change it, or a better / cheaper one came along that they switched to - but the basic design of it - a chip on a board with minor support components - can't really change.

The reason it's hard to find the differences between the different revisions is because those differences are so inconsequential to the end user that knowing them is irrelevant. The only real way you'd find the differences would be to compare the schematics of each revision to find the components that have changed. In some cases it may even just be a change to the silk screening in re-branding from Arduino to Genuino, or just a slightly more modern logo, etc.

It's still the same chip, and still connected up in the same way.