# $any.id.levels: logical. Is there any identical levels? (NULL if data1 and data2 are not factors)
# $any.id.levels: logical. Is there any identical levels? (NULL if data1 and data2 are not factors)
# $same.levels.pos1: position, in data1, of the levels identical in data2 (NULL if data1 and data2 are not factors)
# $same.levels.pos1: position, in data1, of the levels identical in data2 (NULL if data1 and data2 are not factors)
# $same.levels.pos2: position, in data2, of the levels identical in data1 (NULL if data1 and data2 are not factors)
# $same.levels.pos2: position, in data2, of the levels identical in data1 (NULL if data1 and data2 are not factors)
# $common.levels: common levels between data1 and data2 (can be a subset of $levels or not). NULL if no common levels or if data1 and data2 are not factors
# $same.name: logical. Are element names identical ?
# $same.name: logical. Are element names identical ?
# $name: name of elements of the 2 datasets if identical (NULL otherwise)
# $name: name of elements of the 2 datasets if identical (NULL otherwise)
# $any.id.name: logical. Is there any element names identical ?
# $any.id.name: logical. Is there any element names identical ?
# $same.name.pos1: position, in data1, of the element names identical in data2
# $same.name.pos1: position, in data1, of the element names identical in data2
# $same.name.pos2: position, in data2, of the elements names identical in data1
# $same.name.pos2: position, in data2, of the elements names identical in data1
# $common.names: common element names between data1 and data2 (can be a subset of $name or not). NULL if no common element names
# $any.id.element: logical. is there any identical elements ?
# $any.id.element: logical. is there any identical elements ?
# $same.element.pos1: position, in data1, of the elements identical in data2
# $same.element.pos1: position, in data1, of the elements identical in data2
# $same.element.pos2: position, in data2, of the elements identical in data1
# $same.element.pos2: position, in data2, of the elements identical in data1
# $common.elements: common elements between data1 and data2. NULL if no common elements
# $identical.object: logical. Are objects identical (kind of object, element names and content)?
# $identical.object: logical. Are objects identical (kind of object, element names and content)?
# $identical.content: logical. Are content objects identical (identical elements excluding kind of object and element names)?
# $identical.content: logical. Are content objects identical (identical elements excluding kind of object and element names)?