usability,configuration, compatibility(forward & backward),
End to end testing :
is similar to system testing : involves testing of a complete application environment in a situation that mimics real-world use, such as interacting with a database, using network communications, or interacting with other hardware, applications, or systems if appropriate.
UAT: [User Acceptance Testing]
Once the application is ready to be released the crucial step is User Acceptance Testing.
In this step a group representing a cross section of end users tests the application.
The user acceptance testing is done using real world scenarios and perceptions relevant to the end users.
System Testing: Testing conducted on a complete, integrated system to evaluate the system's compliance with its specified requirements. End to End testing: The entire project, i.e which has many integrated systems, are tested. Testing of complete application environment such as interacting with database,using network communication or interacting with other h/w & so on.