When is it appropriate to delete an instance vs resetting it?
From my understanding, deleting an instance removes it completely. Resetting it does the same thing as delete except "reprovisions" it.
What is meant by "reprovisioning" it?
Delete - removes the entire organization from your tenant, you lost it & don’t need again
Reset - just removes your customizations (if any made), like Form UI changes, navigation menu or ribbon changes, JavaScript, workflows or plugins will be washed out. The org will go to its original OOB vanilla state to start over
Provisioning or Reprovisioning is nothing but spinning the SaaS with its factory settings :)