While Napoleon and Snowball have different personalities, they share a number of common characteristics. They both have aspirations of leadership, for example, as we see in Chapter Two when they assume control of the preparations for the forthcoming rebellion. These preparations also demonstrate their intelligence, as shown by their work on the development of Animalism.
In addition, both Napoleon and Snowball are ambitious. For Snowball, this is expressed through his many education committees, designed to aid the intellectual development of the other animals. In contrast, Napoleon demonstrates his ambition when he steals the cows' milk so that the pigs can have it in their mash.
When the two pigs go head to head over the windmill, we get a sense of how competitive they are and neither one is prepared to concede to the other. This demonstrates their mutual stubbornness and ultimately leads to the breakdown of their relationship and Snowball's violent expulsion.