The drive can be a stand alone unit which can be connected to a system and the user will manually insert and swap the tape cartridges as required.
Autoloader
The autoloader contains one tape drive and robotics that can insert and change the tapes. This system is ideal when one drive is sufficient for the read/write performance requirement, but multiple tapes will be required for either capacity or version control.
Tape Library
The tape library contains multiple tape drives and robotics that can insert and change the tapes. This system is ideal when multiple drives are required to maintain the read/write performance requirement, and multiple tapes are required for either capacity or version control.
The solution used will depend on the business and application requirements. If an application needs to be backed up each night, and the amount of data to be stored will fit on a single tape and the window is such that a single drive can support the transfer, then an autoloader will meet the requirement and not require any manual intervention.
If an application required multiple data streams to meet the transfer rate, then a tape library might be more suitable as it contains multiple drives to support the interleaved data streams and also multiple tapes to meet the storage capacity.