my passcode or face id recog is not working after the update

what is the difference between Update vs Restore? thougth retore completely wipe the phone and reset to orig and all data is lost...vs Update, retain data. should I use the Update to keep it clean, in case the recent update was not successfully installed thus causing my iphone to not recognize my passcode? this was due to recent update after i plugged in the phone to charger, thus it downloaded the updated, installed (without my consent), and restarted the phone (thus face recognition was not until i entered the passcode after a restart....) this is so frutrating