Try/Finally block vs calling dispose?

Is there any difference between these two code samples and if not, why does using exist?

StreamWriter writer;
try {
    writer = new StreamWriter(...)
    writer.blahblah();

} finally {
    writer.Dispose();
}

vs:

using (Streamwriter writer = new Streamwriter(...)) {
    writer.blahblah
}

I mean in the second example you really should be putting it in a try block anyway so adding the finally block really doesn't use much more effort. I get that the entire thing might be encompassed in a bigger try block but yeah, just seems superfluous to me.