But similarity in a few laws does not mean similarity in the basic nature of the academic discipline. The fundamental difference between physics and economics is that physics deals with the physical universe which is governed by immutable laws, beyond the pale of human behaviour. Economics, in contrast, is a social science whose laws are influenced by human behaviour.
Simply put, I cannot change the mass of an electron no matter how I behave but I can change the price of a derivative by my behaviour. The laws of physics are universal in space and time. The laws of economics are very much a function of the context.