Here's an example of Beyond Compare in response to a Retrieve for Merge configured to show orphans only:

In this case I'd probably decide that I want ApexDocExample and UnresolvableReferenceTest locally, should deploy formRenderer.js to the server, can remove ServerOnlyClass from the server, and can remove LocalOnlyClass locally. I'd copy the first two left-to-right and delete LocalOnlyClass.cls* in the right pane from within Beyond Compare, then I'd deploy the form Lightning component and delete ServerOnlyClass from the server.
Hopefully that makes it more concrete.
Regards,
Scott