Google Storage uses a hierarchical structure to store buckets and objects. All buckets are in this one environment, and all objects are also inside a hierarchy within a certain bucket. Based on this hierarchical structure, a bucket name has to be unique across all the existing Google Storage buckets. Each bucket name must be unique across the entire Cloud storage namespace. 

To name a bucket, we cannot use a name that has already been chosen by another user. While objects must have a unique name only within a given bucket, we can therefore have multiple buckets that always contain an object with the same name.