• Normal backs up all files and marks each as backed up.
• Copy backs up files but does not mark them as backed up.
• Incremental backs up files only if they were created or modified since the last backup operation completed and marks them as backed up.
• Differential backs up only those files created since the last backup completed, but unlike Incremental backups, a Differential backup doesn't mark the files as backed up.
• Daily backs up only files created or modified that day (without changing files' archive bits).
• This is where i found this Info.
•  http://articles.techrepublic.com.com/5100-10878_11-6104186.html

Thanks Dave5.

Every little bit helps.