There is a BIG difference between iCloud Backup and iCloud Sync. Go to Settings/<your name>/iCloud. Any switches that turn on will sync the associated content to iCloud.
If you go to Backup in that same screen you can create an iCloud backup. Other than the fact that it also resides in iCloud, it has nothing to do with the data that you synced by turning on those switches. And, in fact, any type of data whose switch is on will not be saved in your iCloud backup, because to do so would be redundant.
If log out of iCloud (your Apple ID) you are given the choice of keeping the synced data or removing it. Remember, that is synced, not iCloud backup I'm talking about. You should generally choose to remove it to avoid duplicates later when you log in again.