Major version change (1.x.x -> 2.0.0): this would represent a completely new edition, a full rulebook rewrite, or even a full game reboot.
Minor version change (1.0.x -> 1.1.0): this would represent one or more changes big enough to require or warrant character rebuilds.
Patch version change (1.0.0 -> 1.0.1): this would represent changes small enough to not change how characters are built, new and important clarifications, or other small updates.
Additionally, the rulebook displays the date it was last revised. If that date changes without a version number change, then something inconsequential was changed, like spelling or grammar errors getting fixed.
This post is a collection of all threads of past/current rulebook releases.
Version numbers:
Additionally, the rulebook displays the date it was last revised. If that date changes without a version number change, then something inconsequential was changed, like spelling or grammar errors getting fixed.
Rulebook