What's the difference between backup copy and backup archive?

Backup copy is used to make duplicate version of your backup data to secondary storage or location, the copied data is usually of the same version, size and type of your original backup data. 

While backup archive feature is used to archive your backup data to a more cost-effective storage for long-term preservation. The archived backups are always full backup files (full restore points), no matter it is created from full, incremental or differential restore points.