From Halopedia, the Halo wiki
Mission playlists, or campaign playlists, in Halo: The Master Chief Collection are a series of campaign levels curated into sets for players' continuous play. Playlists are typically created based on commonalities between levels, such as a specific setting, character, or gameplay aspect. Progression in each playlist are saved between sessions, so players can resume or restart the playlist at any time.
Players' performance in each playlist, including scoring and completion time, are recorded in the "Playlists Scoring" and "Playlists Timing" leaderboards, respectively.
List of Playlists
Halo: Combat Evolved Anniversary
Halo 2: Anniversary
Halo 3: ODST
The following achievements can be unlocked by completing mission playlists in Halo: The Master Chief Collection.