A new earth

As a Christian, my previous preconception of heaven revolved around going or elevating to a "new" place while the current place existed for the "still alive" or maybe non-christians.  Unfortunately, as I've been doing revelations, it's about this current earth is going to be wiped away, and this current earth is transformed/renewed/restored.  In this new earth, God promises Joy, splendor and communion with Him forever in His city.  What is the difference between this new earth and "His city"?