1. Triple Alliance: Germany, Austria-Hungary, Italy. Bismark was the leader, keeping peace, as well as keeping France isolated. Austria-Hungary has a conflict with Russia over the Balkans because they both want to take over the Balkan area. Italy wants Tunisia because in 1881, France had taken Tunisia. Italy was made so it formed an alliance with Germany and A-H. However, Italy eventually leaves because of animosity with A-H. The Central powers of the Triple Alliance were Germany, A-H, Ottomans, and Bulgaria
2. Triple Entente: France, Russia, Great Britain. France wants Alsace-Lorraine back from 1871 during the Franco-Prussian war so it seeks allies. Russia wants the Balkan Peninsula and is against Germany, not friends. Great Britain was threatened by Germany in terms of building up its military. The fact that France and GB are in an alliance together is weird because they had clashed over land in Africa, but then with the Morccan Crisis, Germany became isolated as Bismark brings France and GB together (they share their hatred towards Germany).
With an alliance, one is more likely to fight (think students and unfair test qu's/answers).
Italy and the U.S. will join the Triple Entente later.