Difference between File.separator and slash in paths

Question

What is the difference between using File.separator and a normal / in a Java Path-String?

In contrast to double backslash \\\\

Answer 1

Although it doesn't make much difference on the way in, it does on the way back.

Sure you can use either '/' or '\' in new File(String path), but File.getPath() will only give you one of them.