Xml document header question

Hi all,
It was my understanding that xml document header
<abcd:ABCD xmlns:abcd="abcd.xsd" xmlns:xdb="http://xmlns.oracle.com/xdb" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="abcd.xsd
C:\temp\abcd11.xsd">
<mnop>
...
...
...
</mnop>
</abcd:ABCD>

and

<ABCD xmlns="abcd.xsd" xmlns:xdb="http://xmlns.oracle.com/xdb" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="abcd.xsd
C:\temp\abcd11.xsd">
<mnop>
...
...
...
</mnop>
</ABCD>

are supposed to be the same thing. But XMLSpy does not hold the same opinion... The first one is correct while the second one is wrong... I was wondering what the difference is because in the first case the namespace is named where as in the second case the namespace is default.
Can somebody point out the difference...

Regds,
P