Levels of analysis is a general way of referring to these differences on the whole, because they are different perspectives on the problem. Those 3 levels of analysis are content free, because they could be applied to any field. That is, the micro, molecular and macro levels of analysis can be applied in economics, anthropology, physics, etc. Levels of analysis can also be described on the basis of the content of the analysis. Of course, these levels can interact with each other.
Biological changes can affect cognition, which can affect behaviour.
Typically, researchers focus on only one of the levels, although they recognize that completely understanding any phenomenon requires analysis at all levels. No, no, actually there are clinical psychologists and research psychologists. About half of psychologists are clinical psychologists, or clinicians. The other psychologists are research psychologists, although they may have jobs in several different fields, where research is not the primary focus of their work. Clinical psychologists may also be researchers, but research psychologists cannot be clinicians.