Digital Twin is one of the many components in Industry 4.0. Unfortunately, the meaning of digital twin could be differed from one to another. It is very confusing when someone is asking for a “Digital Twin” solution, what does the person really want? IBM has defined digital twin as virtual representation of component or assembly of components that interact with one another limited for the purpose of product life management. Siemens defined it in three areas namely Product, Production and Performance twins. The name suggested limit the definition to its application and there is no relationship with another. Lastly Jones characterised the term to 19 areas which is too much for one to remember and to know how they are related to one another.  The purpose of the paper is to re-classify digital twin from the perspective of its purpose of implementation.  By knowing the need, we could recommend the level of digital twin to be adopted.