The file comparison (element based) is a pure hash value comparison and includes - in contrast to the pixel MD5 comparison - all metadata and all other elements (not just image elements) into the search.
This search method will find absolutely identical elements. You can specify a minimum and maximum element size.
The MD5-comparison is set by default as hash algorithm (Professional and C/S version have the possibility to change the hash algorithm).
In these both versions you may see this as well: