If you take a look at the photo you can see a good example of the difference between the two...The Golden is more solid with bigger gills. The Smooth is thinner with a wavy cap but not exactly 'smooth'. The gills are still visible, they're just fainter.
The Golden's are generally considered to be better tasting but I believe that's simply because they offer a bigger bite. I'd never turn down a plate of smooth chanterelles.