How is empty node tag in xml and non-existence of node interpreted?

I have two XML request:

<GetPersonRequest>
    <Person/>
    <IncludeAddress>true</IncludeAddress>
</GetPersonRequest>

and

<GetPersonRequest>
    <IncludeAddress>true</IncludeAddress>
</GetPersonRequest>

Is there a difference between empty nodes and non-existence of nodes ? Does the XML parser makes any difference ?. Does call to text of both node returns empty string ?

I w开发者_如何学运维ould like to add that second XML is similar in that element is optional. So the user might just omit. Does xml.getElement("Person") still return null ?

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These XMLs are different. 1st XML contains element Person (empty element, its text() is null), while 2nd doesn't. For 2nd XML (pseudo-code) xml.getElement("Person") will return null.