No difference. The federal government doesn't have the authority to grant or use a warrant in the United States that isn't supported by evidence showing probable cause - FISA warrants included. Congress can't make such a law and courts can't act on it. A FISA warrant requires the court find probable cause that the target of the surveillance is a "foreign power" or an "agent of a foreign power", and that the places at which surveillance is requested is used or will be used by that foreign power or its agent. Probable cause can't be established on the word of an unanimous tip to a newspaper.