Extended data
1, iCloud cloud backup
With a Wi-Fi network connection, you can use iCloud to back up your devices. You can use iCloud for backup without connecting your device to your computer or even going home.
ICloud cloud backup contains almost all the data and settings stored on the device. ICloud cloud backup does not include:
Data stored in iCloud, such as address books, calendars, memos, iCloud photos, iMessage messages and short messages (SMS) and multimedia messages (MMS)*
Data already stored in other cloud services such as Gmail and Exchange mail.
ApplePay information and settings
Touch ID background
ICloud music library and AppStore content (if these contents are still available in iTunesStore, AppStore or AppleBooks Store, you can tap to re-download the content you have purchased. )
Learn how to make iCloud cloud backups, or how to manage iCloud storage space and delete backups that are no longer needed.
* When you use it? When you open an iCloud cloud message, voice memo or iCloud photo, your content will be automatically stored in iCloud.
2.iTunes backup
On a Mac or PC, you can back up devices in iTunes. Synchronizing a device with a computer is different from a backup operation. ITunes backup contains almost all the data and settings stored on the device. ITunes backup does not contain:
Content from iTunesStore and AppStore, or directly downloaded to the PDF of AppleBooks.
Content synced from iTunes, such as imported MP3 or CD, videos, books and photos.
My photo stream.
Face ID or touch ID settings
ApplePay information and settings
"Fitness History", "Health" and "Keychain" data (to back up these contents, you need to use encrypted backup in iTunes. )
Learn how to make backups in iTunes, find backups on a Mac or PC, and delete backups that are no longer needed.
References:
About the backup of iOS devices