Theoretical physics, especially high energy physics, is often further divided into "theory" and "phenomenology". Since both refer to theoretical (not experimental) physics, what exactly the difference between them is? I would say that 1. Theory concerns general principles and methods of theoretical physics, while phenomenology concerns their application to a calculation of quantities that in principle can be directly compared with observations. On the other hand, my colleague said that 2. Theory deals with the well founded theoretical results obtained from first principles, while phenomenology deals with not so well founded effective models with a smaller domain of application. What do you think?