Both treaties concerned events that would happen after the defeat of Germany. The Versailles Treaty had to do with the punishment of Germany and the redrawing of Europe's borders. The Germans found this quite punitive. Some Russians also thought the treaty unfair, as they lost Poland even though their country fought on the winning side for three years before they were forced out by the Russian Revolution. The Versailles Treaty was composed to placate the Allies, mainly France, fearing a strong Germany would once again invade.
Yalta took place before Germany officially surrendered, but it also concerned the redrawing of European borders, though few realized it at the time. Roosevelt agreed to let the Soviets stay in Eastern Europe, thinking that he would allow free elections there. Roosevelt hoped to pressure Stalin on this issue after the war, but he never got the chance.
The people of Eastern Europe thought the treaty highly unfair, trading the oppressive Nazis for the oppressive Soviets. Poland and the Baltic nations would not exist again for nearly fifty years. Yalta was signed in order to placate the Soviets who wanted a buffer zone between themselves and the West. Roosevelt agreed to it because he wanted an assurance that the Soviets would assist in the war against Japan.
The main similarity between the two treaties were that both were signed without listening to the wishes of the people who would actually have to abide by them. They were both instrumental in redrawing the maps of Central and Eastern Europe.