Differences between XmlReader, StreamReader and StringReader in deserialization

I asked the following question here in stackoverflow link question .

During the deserialization, depending on the stream you use, an error can occur in the XML namespaces, depending on the question link.

Examples of the code that has the namespace error.

byte[] buffer = Convert.FromBase64String(base64);
        MemoryStream ms = new MemoryStream(buffer);
        XmlDocument doc = new XmlDocument();
        doc.Load(ms);

        XmlSerializer _xmlSerializer = new XmlSerializer(typeof(resNFe));

        XmlReader _reader = new XmlNodeReader(doc);

        //Não funciona  - xmlns:"" não esperado

        var _resNFe = (resNFe)xmlSerializer.Deserialize(_reader);

Code that works:

     // Funciona 100%
    var resnfe = new resNFe();
    string caminho = @"C:\home160604301024000131550010001971591190360567.xml";
    XmlSerializer xmlSerializer = new XmlSerializer(typeof(resNFe));
    StreamReader reader = new StreamReader(caminho);
    resnfe = (resNFe)xmlSerializer.Deserialize(reader);
    reader.Close();

This also works:

public static T LoadFromXMLString<T>(string xmlText)
{
var stringReader = new System.IO.StringReader(xmlText);
var serializer = new XmlSerializer(typeof(T));
return (T)serializer.Deserialize(stringReader);
}

Remembering that the same XML and the same serialized class are being used.

Does anyone know why this namespace error depends on the stream used?

XmlDocument:

<resNFe xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" versao="1.00" xmlns="http://www.portalfiscal.inf.br/nfe">
<chNFe>5616516516516516816165165156</chNFe>
<CNPJ>12345678654231</CNPJ>
<xNome>bla bla bla</xNome>
<IE>651651654</IE>
<dhEmi>2016-06-28T09:00:04-03:00</dhEmi>
<tpNF>1</tpNF>
<vNF>10049.69</vNF>
<digVal>asdasdasdzc5asr41fa564s</digVal>
<dhRecbto>2016-06-28T09:16:34-03:00</dhRecbto>
<nProt>3531351313235151</nProt>
<cSitNFe>1</cSitNFe>
</resNFe>