River A river is a collection of drops that have been pulled from disparate channels such as RSS, SMS, Twitter, Email, Facebook etc. It is the point of entry for all drops within the system.
Bucket A bucket is a curated collection of drops that have been hand-picked from a river. Buckets are the focal points of collaboration; a place where various users can add drops of interest e.g. from the same source, cluster around a specific subject matter etc and later share this collection as a newsletter, RSS feed or push it out to a 3rd party service or application such as Crowdmap or an Ushahidi deployment.