Currently only iOS (iPhone, iPad) has expanded view (a setting found in More).
You can see the difference here:
https://irealpro.com/support/support-ios/
Either search 'compact' or 'expanded'

You see the key (also Style, Tempo and Composer) listed with each song title, both in the song index or within a playlist. It is a quick way to check through each song's settings in that playlist.

As Cyrille said, the keys can be different (also playback style, tempo, repeats) in different playlists for the same song, and this applies to all platforms.