Answer
Germany (Central Powers):
Age of most enlisted men: 18-45
Types of people fighting: Rich, poor, educated, illiterate, etc.
Uniforms and gear: Steel helmets, gas masks, leather boots, and grey-green uniforms
Weapons: Mauser Gewehr 98 rifles, Luger P08 pistols, and MG 08 machine guns
Vehicles: Tanks, armored cars, and horse-drawn wagons
United States (Allies):
Age of most enlisted men: 18-45
Types of people fighting: Rich, poor, educated, illiterate, etc.
Uniforms and gear: Steel helmets, gas masks, leather boots, and olive drab uniforms
Weapons: M1903 Springfield rifles, M1911 pistols, and M1917 machine guns
Vehicles: Tanks, armored cars, and trucks.