A collective mark is a trademark or service mark used, or intended to be used, in commerce, by the members of a cooperative, an association, or other collective group or organization, including a mark which indicates membership in a union, an association, or other organization.
A collective mark is used by all members of the collective group and therefore, no single member can own the trademark. The collective organization holds the title to the mark for the benefit of all members of the group.
In comparison, a trademark or service mark is used by the owner of the mark to indicate the commercial source or origin of the goods/services in the owner.