Sorry, close but no cigar, as they say. While a sequence printed on both sides is usually counted in terms of pages, and when printed only on one side is usually counted in terms of leaves, the fundamental definition is that a page constitutes a given face of a leaf and a leaf constitutes the entire piece of paper one turns to progress through a volume.
Per Carter's _ABC for Book Collectors (New Castle: Oak Knoll Press, 2002): Leaf -- The basic bibliographical unit: the piece of paper comprising one page on its front side (recto, obverse) and another on its back (verso, reverse). Per AACR2 (2005 Update). Glossary: Leaf - One of the units into which the original sheet or half sheet of paper, parchment, etc., is folded to form part of a book, pamphlet, journal, etc.; each leaf consists of two pages, one on each side, either or both of which may be blank. John F. Myers, Catalog Librarian Schaffer Library, Union College Schenectady NY 12308 mye...@union.edu<mailto:mye...@union.edu> 518-388-6623 Gene Fieg wrote: A page has printing on both sides A leaf has printing or representations of data on one side. Period.