Difference between Refresh Workspace vs Reset Data – Udacity Support for Accenture

Refreshing your web browser may fix some small Workspace issues. If your Workspace has “gone idle”, you can refresh the page to get a new Workspace, for instance. Your work will not be lost as we autosave work very frequently.
The Refresh Workspace option will give you a new virtual machine (Workspace system) but will restore all your student's files onto it. You can try this if you find your Workspace is unresponsive e.g. you've created an infinite loop in your code.
The Reset Data (Get new content) command will give you a new VM and replace whatever work you have done so far with a copy of the Workspace. This option is only if you want to start over again from scratch.