Unblanched almonds are almonds that have had no processing done to them, other than to remove the shells. In particular, the thin brown 'skins' around the almonds are kept on, as you can see (see picture). This means that they tend to retain a little more nutrition, partly because the skins contain extra antioxidants (around 20 in total), and partly because these unblanched almonds have not been heated at all, and food that has not been heated tends to retain more of its nutrition.