Aperture/Lightroom are work flow tools. But have editing features built in. These tools are probably more than most people use. That said the editing tools within Elements are better and give you more options. Elements has the advantage of being cheaper.
Aperture/Lightroom also have extensive library management built in. Aperture,as it's made by Apple has the advantage of working with all the iApps, so if you want to email an image or add to a Pages document its easy (though to be honest, it really not a big selling point for me).
Aperture and Lightroom are available to trial for 30 days. Elements has a trial, but it doesn't start until 1st July.