Group: A group is a collection of people who create music under a specific name. And usually on a long-term basis. The group's name appears in the name of the track.
Examples of groups: Ame, Pig & Dan, ItaloJohnson, they can also be bands or supergroups such as Moderat.
Collaboration: Collaborators are people who create music together, but unlike a group, they don't collaborate under one specific name. And it's usually on a one-time/temporary basis. A producer might collaborate with:
– Co-producer(s) – co-producing is a type of collaboration between two (or more) producers where each participates as an independent artist, and all their names appear in the track's name. (i.e. Dawning – Dettmann & Klock),
– Composer(s) – who do co-writing and arrangement, contribute with musical ideas such as chord progression and vocal melodies,
– Featured artist(s) – guest artists who usually appear in the title of the track (i.e. "feat. Cool Alien"),
– Lyricist(s) – write lyrics,
– Session artist(s) – can be drummers, guitarists, saxophonists, violinists, etc.,
– And other collaborators, as the list can be long. ;)