Isn't message passing between two nodes in ROS same as interprocess communication between two programs in linux same?

edit

You are correct, the message-passing portion of ROS is inter-process communication (IPC).

I'm not sure which other IPC mechanisms you're looking at, but ROS provides the following additional features in addition to just passing messages:

• message type checking (type name and message version)
• support for many languages: C++, Pytho, Lisp, Java and more!
• seamless use of language-native data structures (no need to explicitly serialize)
• seamless use of multiple publishers and subscribers on a topic (IPC channel)
• Introspection of the type, content and rate of messages on a topic (rostopic command-line tool)
• very easy to create and use multiple topics
• easily expands to work across a network, with no changes to your nodes