A "Lamentation" groups Christ's followers around his lifeless body; a "Pietā" is a Lamentation in which the Virgin cradles the body, as at left. Many Pietās are sculptures that feature only the Virgin, not the other mourners (example).
Lamentations always include the Virgin among the mourners and usually have St. John and St. Mary Magdalene, the latter often at the feet of Christ, as at left and in this example.
One unusual Pietā on a French pilgrimage route places Mary directly in front of the cross, as if she were replacing Christ there.
At left, 15th-century painting from Provence
Other images:
MenuGiotto's 1290 fresco
Giottino's1365 painting
Messina's 15th-century painting
Michelangelo's sculpture
Spanish Pietā sculpture, early 17th century
Italian Pietā sculpture, later 17th century
French altarpiece
Panel in a 1523 altarpiece