Differences between threads and processes yarns differ from traditional processes in which the processes are-generally-independent states carry enough information, and interact only through communication mechanisms given by the system. Moreover, many threads usually share other resources directly. In many operating systems even allow the thread is quicker to switch from one thread to another within the same process to change from one process to another. This phenomenon occurs because the threads share data and address spaces, while the processes, to be independent, do not. When changing from one process to another operating system (through the dispatcher) generates what is known as overhead, which is time wasted by the processor to perform a context switch (context switch), in this case go from execution ( running) to standby (waiting) and place the new running process.In the threads, as part of the same process, to make a change of thread time lost is almost negligible. Operating systems like Windows NT, OS / 2 and Linux (2.5 or above) say they have wireless "cheap" and processes "expensive" while in other systems there is a big difference.