From an old BZPower post (http://www.bzpower.com/story.php?ID=2429)
"The movie appearance of Bionicle characters is less official than the set form - Actually, it's the other way around. The movie appearance of characters is in almost all cases considered the most official of the various versions of the Bionicle characters. Now, this does not mean the set form is unofficial; both forms are totally official. They're two different versions of the same characters, used for different media. While the set form was designed according to real world limitations as to what can be produced in plastic, with LEGO pieces, the movie form is designed more freely, closer to what the Bionicle characters would look like if they were actually alive. Perhaps the most significant example of this is the fact that Bionicle characters have always been said to be biomechanical, having both biological and mechanical components. Well, the set form does not show any biological components. When the MOL movie form of the Toa Nuva was developed, the "bio" was put in; movie characters are shown with some biological components. So in the story, when it comes to exact appearances, that form is the most official of the two."