Regularities are repeated phenomena, either in the form of apparent typing or apparent consistencies in the time order in which events occur; but theories are attempts to model the underlying processes that produce regularities. Every science theorises on the basis of its regularities.
Regularities vs. theories
Hillier, B. (1996, 2007), Space is the Machine: A Configurational Theory of Architecture. Space Syntax: London, UK. pp.4