Not at all. we can't merge intergaratin testing and system testing.

Integration Testing

The purpose of integration testing is that integration of and communication between components.
In addition to test intgration of subsystems or communication between external systems.
This testing may be done by developers, team lead, project manager, and cofigeration managemetn team.
Some times this testing can be devided into two parts

1. Assembly testing: is to test whether all sofware components(related to that project) are integrated or not
2. System integration testing : is to test whether the communication is going on external applications or not.

For example, on a project to develop a set of EJBs for use by external applications, assembly testing could be done to test the integration of the EJBs and the components from which they are built, and system integration could be done to test communication between the EJBs and the external applications.

System Testing

The objectives of system testing are to find defects that are attributable to the behavior of the system as a whole, rather than the behavior of individual components, and to test that the software functions as a complete system.

This level of testing is different from integration testing in that the tests are concerned with the entire system, not just the interactions between components.

Other than system functionality and behavior, system testing may include testing configuration, throughput, security, resource utilization, and performance.