SQL Server offers two date formats for the DATE data type that are considered safe in situations where computer settings differ or when SET DATEFORMAT or SET LANGUAGE are used. These are the ISO and ISO8601 formats.
ISO Dateformat (yyyymmdd) is safe because it works, no matter what the computer settings are. It is also unaffected by SET DATEFORMAT or SET LANGUAGE settings.
Thus, it’s better to use these date formats for all comparison and other DATE manipulation processes.