Types of Columns:

Attribute column -- It holds a flat list of values that are also known as members.
No hierarchical relationship exist between these members,as is the case for members of a hirerachical column.
An attribute column referred to as a presentation column.

Hierarchical column-- Holds data values that are organized using both named levels and parent-child relationships.This column is displayed using a tree like structure.
Hierarchies allow you to drill deeper into the data,to view more detailed information.Examples include Time or Geography.

Hierachical column types:
1.Level Based Hierarchy-- It consists of an ordered set of two or more levels.
For example-- A time hierarchy might have three levels for year,quarter and month.

2.Parent-Child Hierachy -- It consists of values that define the hierarchy in a parent-child realtionship and does not contain named levels.Example: An employee hierarchy might have no levels,but instead have names of employees who are managed by other employees.
Employees can have titles,such as vice president.Vice Presidents might report to other vice presidents and different vice presidents can be at diferent depths in the hierarchy.

Ragged Hierarchy: A hierarchy in which all the lowest level members do not have the same depth.
For Example: A time Hierachy might have data for the current month at the day level,the previous month's data at the month level and the previous 5 years data at quarter level--This type of hierarchy is also known as Unbalanced Hierarchy.
Skip-level Hierachy: A hierarchy in which certain memebrs do not have values for certain higher levels.
For example: In USA,washington dc is not belongs to state but it is city.