Leveled Hierarchy

The simplest type of hierarchy where each child node has only one parent and each node has its own distinctive set of attributes. For example, Country > State > City.

Alternate Hierarchy

Each node has its own distinctive set of attributes but a child node could have multiple parents. For example, City object has both Country and State as parents.

Ragged Hierarchy

Hierarchies where the number of nodes is not fixed. One node could be 5 levels deep and another could be 20. Moreover, all the nodes share the same attribute. It is further divided into self recursive hierarchy and network recursive hierarchy.