The NetBSD developers keep a great CHANGES document up to date with what’s new overall, and even categorize it by architecture and machine when appropriate.
Want to know what changed between 10.1 and 11? Or 10.0 and 10.1? It’s all right there, summarized by the people who did the work.
Want to know what changed between 10.1 and 11? Or 10.0 and 10.1? It’s all right there, summarized by the people who did the work.