Q: If I reset my Macbook Pro to its factory settings and then use my external hard drive to get everything back will my laptop look like it did before I reset it?

So I just recently bought an external hard drive to save all my files and to just have a back up in case something happens. But another sole reason for getting it was because I wanted to get rid of that pesky "other" bar that takes up a majority of my storage space. When I called apple support they told me to purchase an external hard drive to back up my files and then reset the computer. My question is is if I were to reset it and transfer my files back to the laptop will I have to completely set everything back up again? Like will I have to set up my mail, iTunes, iCloud, all the settings, etc. Or will transferring everything back my external hard drive do that all for me?