In Chapter 591, we see Madara Uchiha free himself from the influence of Kabuto's Impure World Resurrection/Reincarnation technique (Edo Tensei), saying that he was able to do this because he knew about the technique's seals.
However, in Chapter 620, we see the inventor of the Impure World Resurrection technique, the second Hokage, Tobirama Senju, wanting to be free of the technique, but was stopped by Orochimaru.
How was it that Tobirama was not able to free himself from the Impure World Resurrection technique, despite being its inventor and knowing all about the technique and its seals, but Madara can?
Credits: Linked images are from Mangastream's scanlations.