How is this used?
Tempo trackers are a stopwatch. You start a tracker when you start working on something, then pause it when you take a break, and log time when you’re done that work.
What are the differences?
Server/DC - Start a tracker from My Work. After stopping it, you have the option to log time via the checkmark button. This will prompt you to assign it to the Jira issue you were working on and convert it to Work Logged. There can only ever be one tracker running per user.
Cloud - Start a Tracker from inside a Jira issue, which immediately assigns it to that issue. You can also start a Tracker from a Jira Dashboard, where there is a new gadget for Time Trackers. From this gadget you can see all of the trackers currently in use and their status (running or paused), as well as interact with the trackers.
What are the benefits on Cloud?
Flexibility - You can have multiple Trackers open at the same time, quickly pause time being logged on one item, and switch to another tracker without having to close and submit the logged time.
Swivel chair reduction - Start a tracker whether you are working off of your Jira Dashboard or in an issue.