The Pro version includes several advanced features that are not available in the free "Lite" version:
Release notes for the 2.19 branch highlighted several improvements: Rainlendar Pro 2.19.0 Build 172
: Some users reported errors when updating from previous versions. It is recommended to completely quit Rainlendar before running the installer. The Pro version includes several advanced features that
: Updated Office 365 integration to use the Microsoft Graph API and added support for Microsoft To Do. organized lists for tasks and events
: Keeps separate, organized lists for tasks and events, allowing for due dates, priorities, and multiple alarms.