The only difference is that DFU mode bypass the boot loader/OS which allows downgrading and recovery mode doesn't bypass it and you can't downgrade. Nowadays, I believe you can even downgrade even on recovery mode compared to older iOS. A fresh install is normally setting up the device as new and manually download all apps and sign into iCloud to resync. If you restore from iCloud, it will redownload all the latest apps and sync various documents etc. The main question is can iCloud backup be corrupted? No idea, it may be possible. I believe sometimes the main battery drain is because of syncing with iCloud. Do you store everything and backup everything to iCloud/iCloud drive? I moved away from iCloud since iOS 10 since I noticed I was missing contacts and contacts info got mixed with each other. I only depend on iCloud for Find My iPhone and Notes only.
Religiously, I will never use reset all settings since I've had bad experience before it can cause more problems and you'll have to manually readjust your settings. I also find I experience much less issues when updating using IPSW via iTunes than OTA except on Watch and 4k TV. I experienced more bugs on 4K TV than my Watch and iOS combined. Normally for any update, I force close all apps and (clear RAM on older devices) before updating using iTunes and after updating. I would let it sit for about a 1 min. Then, turn the device off for a few minutes before I power it back on and use it as normal. If I can, I would use IPSW on Watch and 4K TV too!