Part 1: An aid is where if the country is in need of supplies like food and etc. then the people will support them with the supplies that you need. While a treaty is where the 2 countries agree on something like for example a peace treaty. A treaty is i higher level of partnership than and aid. And an alliance is the highest form of a partnership between countries. An alliance is where say the United States of America attacked Germany, and Germany is in a alliance with Italy, then Italy would go to war with the U.S . well.
Part 2: The U.S. was not in WWI at the beginning, the U.S. Entered World War I on April 6, 1917, the U.S. joined its allies--Britain, France, and Russia--to fight in World War I. Under the command of Major General John J. Pershing, more than 2 million U.S. soldiers fought on battlefields in France. They joined to help their allies.
Part 2: The U.S. was not in WWI at the beginning, the U.S. Entered World War I on April 6, 1917, the U.S. joined its allies--Britain, France, and Russia--to fight in World War I. Under the command of Major General John J. Pershing, more than 2 million U.S. soldiers fought on battlefields in France. They joined to help their allies.