element() vs. node() in XQuery

Question

Can someone tell me the exact difference between node() and element() types in XQuery? The documentation states that element() is an eleme

Answer 1

This works perfectly using Saxon 9.3:

declare namespace my = "my:my";
declare namespace their = "their:their";

declare function my:fun($arg1 as element()) as element() 
{
            $arg1/a
};

declare function their:fun2($arg1 as node()) as node() 
{
            $arg1
};

my:fun(their:fun2(/*) )

when the code above is applied on the following XML document:

the correct result is produced with no error messages:

Update:

The following should work even with the most punctuential static type-checking XQuery implementation:

declare namespace my = "my:my";
declare namespace their = "their:their";

declare function my:fun($arg1 as element()) as element() 
{
            $arg1/a
};

declare function their:fun2($arg1 as node()) as node() 
{
            $arg1
};

 let $vRes :=  their:fun2(/*) 
  (: this prevents our code from runtime crash :)
  return if($vRes instance of  element())
     then
       (: and this assures the static type-checker 
          that the type is element() :)
       my:fun(their:fun2(/*) treat as element())
     else()