A project manager's goal is to ensure project closure. A project manager is teleological. and consequentialist The project manager's worries are scope/schedule/quality.
I don't work as a partner manager, but I suspect that the role is far more open ended. Partner managers should, I believe, work to sustain and improve a partnership. A partner manager's worries involve competition, competitive advantage and trust.
While researching the question, I found "What makes a good Partner manager", which has this excellent quote,
> [Partner management] is also not a project management task. If you go about trying to manage a relationship as a set of activities to be controlled through some formal or semi-formal mechanism, you will not only alienate staff in the partner company, but you will stifle opportunism and innovation in the relationship.