Checks to determine if another instance has the same definition as this instance and
if it does. Derived classes MUST override this method and check
all new fields introduced by the derived class for definitional equivalence. It is NOT necessary
to check base class fields because the base class will already have done that. When overriding this method,
you should NOT call the base implementation because it will return
for all derived-class instances.
Derived classes should check the type of other
to preserve the symmetric nature of IsSameDefinition(Object)