Robotic systems have the potential to enhance a wide range of domains, such as medical workflows, by automating individual steps of complex processes. However, human-robot interaction (HRI) is of critical importance, as effective collaboration between humans and robots is essential even in highly automated environments. Recent research has predominantly focused on the development of interaction methods rather than systematically comparing existing approaches. Therefore, we conducted a user study (n=20) to compare different HRI concepts for end effector manipulation combined with clutching mechanisms for manip-ulation activation in an alignment task using the example of robotic ultrasound (US). Manipulation methods included hand-guiding, teleoperation, and touchless interaction, while clutching mechanisms were realized through hand, voice, and foot interaction. The results indicate advantages of hand-guiding for manipulation. While no significant differences were observed between clutching mechanisms, strong evidence suggests comparable performance across these modalities. Notably, significant interaction effects on perceived workload reveal that the optimal clutching mechanism depends on the selected manipulation technique. This work underscores the critical importance of selecting appropriate HRI concepts and understanding the dependencies of manipulation techniques with clutching mechanisms. While our study included the usage of a robotic US, the insights gained are broadly transferable across various domains involving robotic manipulation tasks in human-robot collaboration.