How does Java run() method work?

Question

Multi-threading in Java is done by defining run() and invoking start().

Start delegates to a native method that launches a thread through operating system routines and

Answer 1

Maybe it is a semantic argument, but a Thread and a Process are not synonymous.

A process is launched by the operating system, and has it's own private code pages (compiled set of code). A Thread is launched from the program internals, and initially shares its parent's code pages (compiled set of code).

That the JVM internally uses a Thread to run the main method is an implementation detail of the environment, but not a representation of the Java language. If a Thread was to report in the main stack frames, the architecture of referring back to the source code position would be impossible, because that main-serving thread would have no compilation unit (it is internal to the JVM).