Factory Reset: Factory resets are generally done to remove the data entirely from a device, the device is to be started again and requires the need of re installation of the software. The factory reset makes the device function again in a new form. It cleans the entire system of the device. It is probably done at the time of updating to a new version of the device’s software. Factory reset is also done after the system update to remove any bugs or interruptions that can be caused in the new updated version due old soft wares. In short it cleans the entire system of the device

Hard Reset: When a device does not function properly, it means the setting in the device needs to be changed, so only that part of the device is reset, or rebooted in the hard reset. It clears all the memory associated with the hardware and updates the hardware with the latest updated version. After the hard reset, the CPU or the processor restarts the application.In hard reset, you clear the entire phone or even update it with other operating system if your phone supports the SD Card based installation. To hard reset, your phone should be turned off then press Vol+ and Power keys together until the menu doesn’t shows up.

In simple ways.. Factory reset- Formating of the os and revert it back to original as it was out from the factory.

Which One Is Recommended Hard Reset or Factory Reset:-

Well both have some what similar functions, but still some times just factory reset won’t solve all your problems. So just do hard reset- a solution for all.