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. There are seven sets of playlists, six game-specific and a seventh cross-game playlist. Every game-specific playlist has a full game playlist for every difficulty and a playlist for LASO (except Halo 3: ODST which has two LASO playlists). Except for LASO playlists and the Legendary Master Chief Saga playlist, all levels are played without skulls.
Certain missions start at later checkpoints. However, they still count towards par time and score achievements, so they can be used to obtain stricter par score or par time achievements by cutting out parts of the mission.
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. The LASO achievements must be completed using the playlists.