The term "registered mail" when used (1) in any section of this Code or of any code of public local laws, (2) in any municipal charter, (3) in any resolution or ordinance of a board of county commissioners or county council of a county, (4) in any resolution or ordinance of the mayor and council, by whatever name known, of a municipal corporation, or (5) in a rule, regulation, or directive of a department, board, commission, or other agency of this State or of one of its political subdivisions, includes and may be applied as the term "certified mail". Both terms mean the uses, procedures, and fees provided and generally referred to by the United States Post Office Department. A provision in any such law, charter, resolution, ordinance, rule, regulation, or directive, for the use of one type of such mail, may be interpreted and applied to authorize the use of the other type of such mail as an alternate.