XML Serialization makes it possible to convert any common language runtime objects into XML documents or streams and vise versa.
The XML Serialization enables it to convert XML documents into such a meaningful format that the programming languages can process the converted documents with ease.
Binary serialization converts the files to a binay format. In this case all the data get converted into a binary format which is not a human readable format. In binary serialization entire object state is saved, instance identity is preserved and it graphs with multiple references can be handled in this.
XML serialization doesnt allow these things.