Almost the same, but ながら puts weight on the previous action, or on both equally; "見ながら" 宿題をします / "見ながら" "宿題をします". On the other hand,つつ on the second action; 見つつ "宿題をします"
By the way, before answered, I looked it up online, and found some different explanations. Still, the one above feels right for me.