Social Media Share Buttons
The social media share buttons are the buttons that go on your products that say: "like it", "share it", "pin it" and "tweet it". This way your customers can show your products on THEIR social media pages. You can turn these on through Administration / Social Media.
Social Media Icons
The social media icons that show up on your site (generally under the left menu) are linked to your own social media pages. You can add those links through Administration / Social Media.