Liz Pelly, in a fantastic article about the secret lives of playlists:

Not all Spotify playlists are created equally. To begin understanding this, look at them closely. Literally. Choose a playlist in Browse, and look at its cover art. Look in the corner for a logo. Look at another. Look at all of them.The vast majority of their square, tinted, Instagram-like front covers will wear a tiny Spotify insignia, that little circle with slanted waves—the artist who designed the logo says it is a visualization of streaming. On other playlists, you’ll occasionally notice different logos: the thick cursive word Filtr, the all-caps logo for Topsify, or simple rounded text reading Digster. These are the playlisting brands owned by the major labels: Filtr by Sony, Topsify by Warner, and Digster by Universal. Very rarely you might see an independent label or brand logo.

And:

Pay-to-playlist is real. For labels to influence Spotify-created playlists, Jeff describes a whole network of back-scratching and gatekeeping. While money might not be directly changing hands between majors and Spotify for direct access to playlist, there is a bigger picture where labels and Spotify provide value for each other – things like driving social traffic by getting artists to post Spotify links, doing paid media, and advertising. “If you can go to these [streaming] accounts and say, we have a $5,000 ad plan, and we are going to drive exclusively to Spotify…” he explains. Well, isn’t that a relationship they will want to keep mutually beneficial?