Using Synch to compare two folders and deleting but keeping files

Drive B has all the files on A plus some additional ones, some that I want to keep and some that I want to delete.
I therefore need to identify the files on B that are not on A, go though them manually removing the ones that can be deleted. Once I have done that I can do a two way synch.
What I don't see how to do is to identify this list of files to then go through them manually. One blunderbuss method is to use (eg) Duplicate Cleaner to identify duplicates between A & B and delete all those on B. What is left is the list of files I need to check.
An easier way would be to use Dopus One way copy of A to B with delete files not on A if there was a way of not actually deleting them but moving them to a temporary folder. Is that possible?

Doing a one-way sync comparison, with the delete option on, will give you a list of files in the destination that don't exist in the source.

Don't do the actual sync, just the comparison stage.