The video below runs through the difference between the SweetHawk time-based apps to allow you to make a more informed decision about which one is right for you...
Calendar: Provides a central calendar for agents to create, maintain and collaborate on events relevant to specific tickets and their team.
Deadline: Allows you to set a date and time on any ticket. Then you can make stuff happen when the deadline hits.
Due Time: Allows you to set a date and time on any 'Task' ticket. Then you can make stuff happen when the due time hits.
Reminders: Allow your agents to set reminders to pop up messages and get emails at specified times.
Timers: This app allows you to perform down to the minute actions on tickets relative to events that take place on a ticket (eg. when it is created). It is similar in function to Zendesk native automations, but instead of doing things on an hourly basis, you can do things minutely.