They're both important if you are in a large corp.
They both need to praise and recommend you in order for you to be promoted (your manager has more to do on that). A bad word from either will kill any prospect of promotion instantly.
They both need to carry their weight for the team and the department respectively. They put a ceiling on what your team and your department can do and can get (work, budget, opportunities). In a bad case there's simply no slot for promotion so you can't be promoted. In the worst case your team/department might get gutted.
They both need to praise and recommend you in order for you to be promoted (your manager has more to do on that). A bad word from either will kill any prospect of promotion instantly.
They both need to carry their weight for the team and the department respectively. They put a ceiling on what your team and your department can do and can get (work, budget, opportunities). In a bad case there's simply no slot for promotion so you can't be promoted. In the worst case your team/department might get gutted.