DIFS is a great tool for file system migrations. Normally the file system is audited to a data source like Excel or SQL Server. You can then perform any data clean-up and adjustments so that DIFS can then import the documents and meta
data into SharePoint.
Alternatively DIFS allows you to specify a SourceDataSetType of FileSystemFiles which will just copy a folder, subfolders and contents into SharePoint. This is detailed in the documentation.
Please reference to the PDF documentation for full details on how to do this.