There is a difference. A law comes through observation, for example the laws of thermodynamics, there has not (really) been an observation of them being violate

There is a difference. A law comes through observation, for example the laws of thermodynamics, there has not (really) been an observation of them being violated (macro-scale). There's not really a theory underpinning them, mathematically a infinite motion machine could work. But it has been observed that it hasn't and it appears that it can't be violated. That atoms make up all matter is a Theory, it's a model based on hypotheses that have been tested over and over. A different model could be created that may match better (like everything being made of fields and waves). Basically a theory is how, a law is what. [Yes i am aware that atoms don't necessarily conflict with waves]