I disagree. In my industry, the two are synonyms, and quibbling over distinctions is silly. Hero=Main Viewpoint Protagonist. You can write a book without a hero, but it is difficult to do. 99% of the stories we experience have one--and Ocean's 11 is certainly included in the 99. If you want to make a distinction here, simply say you didn't find them very 'heroic' which means something else.
If you'll notice, I said the character's in the movie were PRESENTED as Robin-Hood like characters. The viewers were encouraged not to think about the consequences of the heros' actions. Indeed, the core of the main hero's conflict was enhanced by hinting that his actions were done in the name of love, rather than money. They made several of the characters comedic sidekicks, and even threw in a small 'apprentice' storyline.
The 'hero' of a story is completely dependent on viewpoint presentation. This story, if told with the exact same events, could be shown from the casino-owner's viewpoint. If we were made to empathize with him as he struggled to protect his casino from bandits, he would instead become the hero of the story--if a tragic one. The same could be done for a police man, or some random worker in the casino.
The person with whom the reader/viewer is made to empathize becomes the hero of the story. The only exception to this are anti-heroes, for whom our empathy may grow, but so does our level of discomfort. In the end, when an Anti-Hero fails, we are glad, though we often pity him at the same time. Michael Douglas in "Falling Down" is a wonderful example.
