How do I identify files NOT in backup drive

[Sigurd]

I want to make drive E: the definitive backup file. In other words E; will contain one copy of every file I have.
All duplicates in Drive E have been removed. I now want to move all files in D: that are NOT in E: to E:
To do that I need to compare D: with E: identify unique files in D: not duplicates.
How do I do that?

[DigitalVolcano]

Try the Wizard (Home tab): "Compare drives or folders to find missing or changed files"