Final answer:
Both Robespierre and Louis XVI were executed by guillotine during the tumultuous period of the French Revolution, Louis XVI marking the onset of the Reign of Terror and Robespierre's execution signaling its end.
Step-by-step explanation:
One way in which Robespierre and Louis XVI of France are similar is that both were ultimately executed by the guillotine. Louis XVI was executed at the start of the Reign of Terror, which was a period of extreme violence where many, including the king, were put to death for counterrevolutionary activities or for opposing the new revolutionary government. Later, Robespierre, who initially came to power during the Reign of Terror advocating for republican ideals and leading the Committee of Public Safety, met a similar fate. As opposition to his rule and the violent tactics employed grew, Robespierre was overthrown and executed in 1794, marking the end of the Reign of Terror and transitioning to a more conservative government known as the Directory.