Dear respected Mr. Mender,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
As per your description, when transitioning from Windows OneNote to Mac OneNote, there are some functional differences. OneNote for Mac and OneNote for Windows are different products designed based on different operating systems. Due to the different systems, the features of OneNote on the different two systems are different.
For example, in OneNote 365 for Windows OS, we can save file offline/locally. But using OneNote for Mac OS there is on offline functionality(only sync to cloud location). Here is article for your reference. What's the difference between the OneNote versions? - Microsoft Support
May I know is there a specific feature that you are looking for in both versions?
Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution.
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Waqas Muhammad