Partnership is a classification of business where all the partners own a stake in the company itself. To make a change in ownership, all partners would have to agree and possibly buy out the outgoing partner. If this did not happen, the outgoing cofounder would still have a say in whatever the company did going forward.
In a corporation, the shareholders own the company and an outgoing cofounder wouldn't be as big of an issue because even though he would have a vote in the direction of the company, his vote would only be one of many other shareholders.