Qalendar

Differences between Qalendar and Calendar
The list could be more complete, but hopefully the most important points are present.

(+) denotes an added feature or a positive change. (=) means a different approach or a change that is more likely to be considered for worse. (-) marks a missing feature or some kind of problem.

General

 * (+) Automatic cleanups of events and tasks can be configured separately.
 * (=) Tasks and notes are on par with month, week and agenda in the menu. They can be saved as the active view on exit and restored after reopening.
 * (-) Some settings are missing (first day of week, alarm tone)
 * (-) The birthday calendar cannot be created. However, if you do it in Calendar, birthdays will be displayed in Qalendar too.

Month

 * (+) Swipe left/right to move between years.
 * (=) Clicking on a day from another month shows events for that day (instead of changing to that month).
 * (=) There is no animation, which makes navigating with touch gestures and arrow keys much faster.

Week

 * (+) Scrolling seems smoother.
 * (+) The small colored rectangles which indicate that not all items are in the view do not have dedicated bars on edges of the scrolling area, thus they take only as much space as is really needed.
 * (+) Click on the hours bar to scroll between all-day section and current time.
 * (+) If an alarm is present for an event, the icon is displayed no matter how little space is available. There are also a few other small differences in how contents of a block are laid out.
 * (=) Blocks are wide enough to completely fill a column horizontally. This gives more space for block contents, but makes it impossible to create a new event by a precise click between two events.
 * (=) All-day events are always at the top of the scroll area. This sometimes might be less convenient, but is more predictable and readable.
 * (=) One block is displayed for each task (instead of one block per day). This is only good if the number of tasks is not too large, because otherwise a lot of scrolling is required to reach the lower parts.

Agenda

 * (+) Scrolling seems smoother.
 * (-) It might be slower due to refresh due to suboptimal access to the database.

Agenda/Day

 * (+) Tweaked contents of event icons to be more clear (e.g. 23:00-... instead of 23:59, to indicate that the event does not end on this day)

Tasks

 * (+) Separate window to display all details (like with events).
 * (+) Possibility to enter additional long description.
 * (+) Number of tasks (overdue, incomplete, completed) displayed in window title.
 * (+) Alternative layout to provide more space for summary and show calendar color.
 * (+) Overdue tasks use a color from theme (instead of hardcoded red).
 * (+) Option to hide completed tasks.
 * (+) Option to delete completed tasks.

Date picker

 * (+) Day numbers are supported by weekday names.
 * (-) Details (day name, week number) are blinking when touching other columns, which technically is not completely wrong, but does not make a good impression.