What is the difference between this and http://nbviewer.ipython.org http://nbviewer.ipython.org or https://try.jupyter.org/ https://try.jupyter.org/. I guess it

What is the difference between this and http://nbviewer.ipython.org http://nbviewer.ipython.org or https://try.jupyter.org/ https://try.jupyter.org/. I guess it was built using https://github.com/jupyter/tmpnb https://github.com/jupyter/tmpnb? If so, that must be so generous for the owner offering free compute.