Backup restore an iPhone 5s?

I'm trying to downgrade to an older version of iOS. I recently updated to 8.1 and want to go back to any other 8 version. I was wondering if I backup restore would I go back to an older iOS verison.

You could save all your photos/videos/contacts ect to the iCloud, restore the phone then download back from the icloud… Which you'd need to re download your apps and you'll end up on the version of IOS your phone came with