Final effect is the same – entry which was Removed or Excluded won’t be refactored, the difference is in presentation. After selecting Exclude you keep entry in the Refactoring Preview, but Remove deletes it from that window.
I think that Remove could be useful when you deal with quite large refactoring and marking everything as excluded could lead to unreadable mess.
Keep in mind, that remove action can’t be undone – you have to start new refactoring…