RTOS are -
1. Follow the time line provided to each task. failing finished the task within time line results in error.
2. RTOS has minimal context switching latency.
3. RTOS are scalable. Means RTOS kernel size can be scale based on your functionality need, so smaller footprints.
4. In RTOS each and every task has a priority based on which task will be allocated with resources for particular time.
5. Priority inversion and priority inheritance and other features of RTOS.