types of drives

Could someone please tell me the difference between a backup drive and a external hard drive.Thankyou

If someone is using an external hard drive as a backup drive then there is no difference. A backup drive doesn't necessarily have to be external though. Just because some external drive is labeled as a backup drive doesn't mean it has to be used for backups.

Backup drives could be any drive used to backup your data so when your main drive dies you still have your data.