From MusicBrainz Wiki
Release attributes should apply to most of the tracks on the release. It's OK to have a couple of tracks that do not fit the release attribute, as long as the attribute applies to the release overall.
- Album - An album, perhaps better defined as a "Long Play" (LP) release, generally consists of previously unreleased material. This includes release re-issues, with or without bonus tracks.
- Single - A single typically has one main song and possibly a handful of additional tracks or remixes of the main track. A single is usually named after its main song. A single has different definitions in different markets, so if you are unsure please check the ReleaseAttributes page.
- EP - An EP is a so-called "Extended Play" release and often contains the letters EP in the title.
- Compilation - A compilation is a collection of previously released tracks by one or more artists. Please note that this is a simplified description of a compilation. If you are unsure, please refer to the full description on the ReleaseTypes page.
- Soundtrack - A soundtrack is the musical score to a movie, TV series, stage show, computer game etc.
- Spokenword - Non-music spoken word releases.
- Interview - An interview release contains an interview, generally with an Artist.
- Audiobook - An audiobook is a book read by a narrator without music.
- Live - A release that was recorded live.
- Remix - A release that primarily contains remixed material.
- Other - Any release that does not fit or can't decisively be placed in any of the categories above.
- Official - Any release officially sanctioned by the artist and/or their record company. (Most releases will fit into this category.)
- Promotion - A giveaway release or a release intended to promote an upcoming official release. (e.g. prerelease albums or releases included with a magazine, versions supplied to radio DJs for air-play, etc).
- Bootleg - An unofficial/underground release that was not sanctioned by the artist and/or the record company.
- Pseudo-Release - A pseudo-release is a duplicate release for translation/transliteration purposes that does not appear on an actual release as described on TranslationTransliterationRelationshipType.