C#

 public void abcMethod1()
{
   string expected = @"http://xyz.aspx";
   string actual = ...; // get the actual value here
   Assert.AreSame(expected, actual);
}

sort A
sort B
loop {
   get a from A
   get b from B
   if a < b
      "Only in A: " + a
      advance A
   else if b < a
      "Only in B: " + b
      advance B
   else
      advance A
      advance B
}

KatNel wrote:

I should also mention that the lists could be different lengths.

Collection common=new Collection();
foreach(object i in a.Clone()) {
    if (b.Contains(i)) {
        a.Remove(i);
        b.Remove(i);
        common.Add(i);
    }
}