A salesperson is accountable for his quota. While this means he needs to put in a certain amount of efforts in the right place, at times success and failure may be out of control.
An engineer is responsible for delivering something that works. While he needs to stay up on new technologies and troubleshoot issues, at times success and failure may be out of control.
Both are accountable for different parts of a project. Both have items that can slip out of control. Both should seek to minimize that part which is out of their control.