Question

according to msdn

IStructuralEquatable

Defines methods to support the comparison of objects for structural
equality. Structural equality means that two objects are equal because
they have equal values. It differs from reference equality, which
indicates that two object references are equal because they reference
the same physical object.

isnt it what Equals should do ? ( when overriding IEquatable) ?

Answer 1

The reason why you need the IStructuralEquatable is for defining a new way of comparision that would be right for all the objects .

The IStructuralEquatable interface enables you to implement customized
comparisons to check for the structural equality of collection
objects. That is, you can create your own definition of structural
equality and specify that this definition be used with a collection
type that accepts the IStructuralEquatable interface.

For example if you want a list that will sort all its elements by a specific definition.
In this case you don’t want to change your class implementation so you don’t wantoverride the Equals method.

this will define a general way to compare objects in your application.