There are two different levels of EXEC commands, the User EXEC level and the Privileged EXEC level. The User EXEC level commands are at the top, or most basic level, of the CLI hierarchy. These are the first commands that you have access to when connected to the device through the CLI. At this level, you can view basic system information and verify connectivity but cannot make any changes to the device configuration.
To make changes to the configuration, you must move to deeper levels of the CLI hierarchy. This is accomplished by the User EXEC level command
enable. This command takes you to the Privileged EXEC level, from which you can reach the configuration command levels.
The Privileged EXEC level commands primarily enable you to transfer and store software images and configuration files between the network and the system, and review the configuration.