The INET framework is an open-source communication networks simulation package for the OMNeT++/OMNEST simulation environment. The INET framework contains models for several Internet protocols: beyond TCP and IP there is UDP,
Ethernet, PPP and MPLS with LDP and RSVP-TE signalling. See the CREDITS file for the names of people involved in the development.
The INET Framework is successor of the IPSuite, originally developed at the University of Karlsruhe and also contains MPLS/LDP/RSVP-TE models from Xuan Thang Nguyen, UT Sydney. If you're asking what's the difference between the INET Framework and the original IPSuite, the answer is: everything -- check IPSuiteLogOfChanges.