You are totally correct on your guess, the 11th of November 1918 is the armistice which by definition is a ceasefire treaty and not a peace treaty per se. The official peace treaty was signed the 28th of June 1919 at Versailles (Treaty of Versailles). Most commemoration and memorial buildings only reflects the dates of the "actual war" (I mean by that the exchange of fire), it's quite rare (from my experience) to see memorials indicating the official dates.

Although I'm making a very vulgarisation in my comment, the real difference between the terms are the following :

• ceasefire : stop or interruption of the hostilities in time of war. It is bilateral.
• armistice : end of war, usually correlated to capitulation and often considered as humiliating, because contrary to the peace treaty, the different parties involved don't all do concession. In other words it's the first step toward a peace treaty, it marks the end of the war. It's very similar to the capitulation but the difference is in that the capitulation is not Nationwide and is done by the army. A city, a garnison, a province, a state can capitulate. It can be considered as treason also since it's the army that gives up and not the country/government. Armistice : political. Capitulation : military/army.
• peace treaty : it's a contract between two or more party with usually conditions and concessions for and from all the sides. Most of the time they are made between countries, but that can also include other moral individual (such as international organisation). I won't go too much in detail because my knowledge in law is not that deep, but the key word here for sure is the word "contract," in law that implies a multitude of things and rules.

I don't know what's the name in England for November 11th, but in France it's "l'Armistice de 1918" (the Armistice of 1918) and not "the end of the Great War/World War I." The confusion is totally legitimate though, most of the time countries celebrate the armistice and not the peace treaty signed (which makes sense when we think about it, peace treaty being contracts require time to be put into legal words so they happen later).