Gnome was seeking in Microsoft style to 'dumb' down names.
Microsoft Money
Microsoft Word
Most application names do not name what the application does simply because simple self-describing names are few and applications are many.
Spotify
Clementine
Nautilus is still named Nautilus. But it is labeled "Files" in the app menu instead of Nautilus. The hope being that people would locate it easier.
Nemo is a fork of Nautilus.
If running them from terminal, you must use the name, not the label
nautilus
nemo