What is the difference between "vlc" and "VLC media player" in Ubuntu Software in Ubuntu 16.04? [duplicate]

The one titled "vlc" is a snap package. You can verify that checking its source, it should say something like "Snap Store".

You can use any of them.

In Ubuntu 18.04 the VLC apt package and the VLC snap package are both the same version 3.0. In Ubuntu 14.04, 16.04 and 17.10 the newer version of VLC that is installed by the VLC snap package can play Blu-ray disks and the older version of VLC that is installed by the VLC apt package can't play them. Some users prefer the graphical interface of the VLC apt package to the graphical interface of the VLC snap package. It is possible to install the VLC apt package and the VLC snap package alongside each other and use them both.