You will be able to see when editing your profile.
In Contributor to: You can add links of sites or companies where you have worked or contributed. You can add more than one links.
Recommended links: You can add links of your favorite sites. More than one link can be added.
Adding link is same and easy just like you added Other profiles links.
You can also change the privacy of Contributor, Recommended links to Anyone on the web, Extended circles, Your circles, Only you or Selected people.