- New dimensions in UML2.0
The major difference is the enhancement and additional features added to the diagrams in UML2.0
Sequence diagram is a time dependent view of the interaction between objects to accomplish a behavioral goal of the system. The time sequence is similar to the earlier version of sequence diagram.
Communication diagram is a new name added in UML2.0. A Communication diagram is a structural view of the messaging between objects, taken from the Collaboration diagram concept of UML 1.4 and earlier versions. This can be defined as a modified version of collaboration diagram.
Interaction Overview diagram is also a new addition in UML2.0. An Interaction Overview diagram describes a high-level view of a group of interactions combined into a logic sequence, including flow-control logic to navigate between the interactions.
Timing diagram is also added in UML2.0. It is an optional diagram designed to specify the time constraints on messages sent and received in the course of an interaction.
if we analyze the new diagrams then it is clear that all the diagrams are created based upon the interaction diagrams described in the earlier versions
http://www.tutorialspoint.com/uml/uml_2_overview.htm
- some of the new notations added to the class diagram from UML 1.x.
Instances
When modeling a system's structure it is sometimes useful to show example instances of the classes.
To model this, UML 2 provides the instance specification element, which shows interesting information using example (or real) instances in the system.
However, merely showing some instances without their relationship is not very useful; therefore, UML 2 allows for the modeling of the relationships/associations at the instance level as well
http://www.ibm.com/developerworks/rational/library/content/RationalEdge/sep04/bell/#N1031B
