The terms used to describe file recovery seem to vary greatly. Usually this is due to the great diversity of file recovery needs and causes. When one has lost important files due to a virus or a compression problem they tend to address the problem as needing to restore deleted files.
Restore deleted files implies that the files in question are available but damaged. In truth this is not the case once a file is sufficiently corrupted so as not to open it is no longer displayed on a list of files. A third party program for file recovery must be used. In contrast when we speak of wanting to retrieve deleted files we usually know where they were left. Generally we retrieve deleted files from external drives such as USB flash drives or camera smart cards. These are more than likely deleted files. Another use for the term retrieve deleted files is when we have a hard drive that has suffered a logic crash oddly enough the files we want to retrieve in this situation are usually not deleted at all. They are merely locked away in a faulty hard drive. The files to access said drive having themselves been corrupted. So what we are really hoping to accomplish is better termed, file recovery or data recovery. We do sometimes need to find deleted files but this is only a portion of data recovery. Consider however that, in a situation where you have mindlessly deleted files you had wanted to save; the task becomes to find and recover deleted files.