Well, terming historical events a revolution is a bit tricky and one in which both historians and sociologists struggled tried to come up with a workable definition. Theda Skocpol came up with one of the more common definitions in her classic States and Social Revolutions:

Social revolutions are rapid, basic transformations of a society's state and class structures; and they are accompanied and in part carried through by class-based revolts from below. Social revolutions are set apart from other sorts of conflicts and transformative processes above all by the combination of two coincidences: the coincidence of societal structural change with class upheaval; and the coincidence of political with social transformation.

States and Social Revolutions of course is a somewhat dated text and Skocpol's historical sociology of both the Chinese and Russian Revolutions is faulty at places, but as far as definitions go, she came up with a workmanlike one. Her definition gives proper focus onto the speed of the process of a revolution ("rapid") but also focuses on how revolutions change the political ("state" aka government) and the social ("class structures"). While Skocpol's focus on class is notable in States and Social Revolutions, one can stretch her definition to include other aspects of the social order such as gender relations, cultural politics, or identity such as going from subjects of a monarch to citizens of a republic. Moreover, her definition is useful in that zeroes in on the macro-processes of fundamental changes in the social order. In order for an event to be a revolution it has to affect significant changes to the structures of society and that is a perfectly reasonable benchmark for the term.

Definitions like Skocpol's can lead to certain rhetorical traps or No True Scotsman fallacies, so like the Pirate's Code, such definitions should be taken as guidelines rather than ironclad rules for understanding historical events. But one of the useful aspects of Skocpol's definition is that it does separate out coups or other forced transfers in political power from events that were much more transformative. A coup d'etat is in the literal sense of the word a replacement of the executive machinery of a state with another form of leadership. Skocpol's definition forces a concentration upon the question of did this change in leadership fundamentally transform society. Many coup leaders will frame their actions as a component of a revolutionary movement, but as the The Who aptly put it, the outcomes of these coups are more like "meet the new boss. Same as the old boss." This is common for military-led coups in which the elites of the old regime are co-opted and the socio-political status quo is reinforced rather than altered. Looking at outcomes and processes rather than just changes in leadership is a much more productive means to analyze events and whether or not they meet the criteria that marks a revolution.