If The first item in the comparison cannot be cast to an IStructuralEquatable object (in other words, if it is not a collection object that implements the IStructuralEquatable interface), it calls the item's Equals method. I had the same question. When I ran LBushkin's example I was surprised to see https://caidenerbiq.sasugawiki.com/6421385/2_dakika_kural_için_c_structuralcomparisons_kullanımı