The key difference in the ‘new’ list is there in line with your title:
Notebook 7+ is built on top of JupyterLab components and so it is more modern and has additional features & abilities. The developers have endeavored to keep the same functionality; however, sometimes it is accessed in different ways than before and some of the functionality is still being made to be consistent.
If you want the older interface, you are looking for NbClassic.
See my answer here to ‘New Jupyter Notebook Interface’ for more about how the ecosystem has changed in the last few months so that you can consider your options from an informed perspective.