Backup Mode

Here is a brief description about Full Backup, Incremental Backup, All Backup

backup_mode = full
This is a full database backup. It is also referred to as a level 0 backup. This backup contains all database files (for offline backup, as well as the online redo log files) and is used as the basis for your following incremental backups.

backup_mode = incr
This is an incremental database backup. It is also referred to as a level 1 backup. This backup contains only the Oracle blocks of all database files that have been changed since the last full backup (for offline backup, as well as the online redo log files).

Compare:
backup_mode = all
This is a whole database backup. This backup contains all database files (for offline backup as well as the online redo log files), yet it cannot serve as the basis for your following incremental backups. Therefore, the scope of the backup is the same as a full backup. The main difference to a full backup is that a full backup is additionally flagged as level 0 in the Oracle control file.

Full backups and whole backups are referred to as complete backups.
Partial (backup_mode = <Object_list>) and whole backups (backup_mode = all) are also referred to as normal backups because they cannot be part of an incremental backup strategy.

Normal and full backups can be performed with or without RMAN (see init<SID>.sap parameter tape_copy_cmd or disk_copy_cmd). Incremental backups are always performed with RMAN.