Notwithstanding the business process modelling notation (BPMN) has gained increasing popularity in the context of business process management; a foundation for verifying the equivalences of BPMN processes remains an open research problem. The capacity to prove that two structurally different graphical representations of a business process are behaviourally equivalent using mathematical founded methods is important during the modelling and design of workflows. In this study, various forms of equivalences are formally defined and studied.