This study attempts to provide guidance in understanding the difference between acts of terrorism on the one hand and war crimes and crimes against humanity, on the other, the latter two collectively referred to as crimes against international peace and security. A clear understanding of the distinction between these two broad categories is important. Not only is there is a need for forensic clarity in doctrinal thought, the fact is that different categories of crimes entail the application of two different sets of laws and precepts, namely domestic criminal systems and international law. The existence, nature, scope and extent of the culpability of the accused will be determined by applying the correct set of legal principles and rules. While it focuses on the major distinguishing features of these two categories of crimes, this study also highlights areas of overlap which cannot be ignored. Analytical conclusions are presented by setting out a number of paradigms with examples. Each paradigm consists of eight essential elements, and the presence or absence of these elements in different combinations in each paradigm can be used to determine not only the legal category of the impugned act but also the existence or otherwise of the culpability of the accused in law.