A Primary Artist is the principal artist(s) or band(s) who participate in every track of the release. Generally, if an artist is credited on the cover art and had a hand in composing the work, they should be included on the album and track level as Primary Artists. On Spotify, a primary artist will be displayed next to your artist name below the track. The artist name associate with your account will always be credited as a primary artist on every release through Unchained Music.
A Featured Artist are the artists who accompany the primary artist in the release. In the case of an multi-release album, the use of this role generally implies that the featuring artist did not have a hand in composing a majority of the album, and is present on a minority of the tracks within the album. On Spotify, a featured artist will be displayed as ft. (ARTIST NAME) in the title.