The version available on github will often have extra features that aren't yet in the release.
The documentation on this site will usually match the code on github. This means it should basically match what is on PyPI, but it might cover new features that haven't been released yet.
Minor breaking change - rectangles now use a single tuple parameter (x, y) to set the corner position, rather than separate x, y parameters. This is for consistency with other drawing objects.
v2.1 1 Aug 2020
Fix a few naming inconsistencies, for example using camelCase rather than snake_case. These have been tidied up to improve things moving forward.
Add Geometry module for drawing shapes.
These break v2.0 code slightly.
v2.0 26 July 2020
Use native Pycairo calls to draw, which adds a lot of new capabilities compared to V1.x. This is a major change that will require changes to any code based on v1.x.
Color module also has new features for modifying colours.
V1.x
Older versions used a different drawing model, wrapping the underlying Pycairo calls to emulate Processing.
This seemed like a good idea at the time, but created a lot of extra work for relatively little benefit, and ultimately made the drawing model less capable that it could be. Use a later version if you can.