Performing a reset on your instance is similar to pressing the reset button on your computer, which wipes the memory contents of the machine and resets the virtual machine to its initial state and restart happen, if you have stopped a virtual machine instance, you restart the instance with its original configuration.
The start method restarts an instance in a TERMINATED state, whereas methods such as reset() and sudo reboot only works on instances that are currently running. In order get more information on reset an instance or stop and then start the instance, I would recommend you to check
this article.