From a data standpoint, a soft off will shut the computer down like a hibernation shutdown. What was stored in memory will get written to disk. A forced or hard shutdown wipes everything from memory. So if there was apps still open or work was not saved, you will lose that data. That part is correct.
But (and this is a huge one. No pun intended) If you're only shutting down your PC in mind to protect it from a power surge, think again. Shutting it down only puts it to sleep effectively. The system is still getting power even when it's fully shutdown. Once it's shutdown, you still have to disconnect the power cord if you want to protect the hardware.