What are the similarities and differences between a trench and a bunker?

Both trenches and bunkers are defensive structures used in military contexts, designed to protect personnel from enemy fire. A trench is typically a long, narrow excavation in the ground that provides cover and allows for movement of troops, while a bunker is a fortified structure, often underground or partially buried, designed to offer more robust protection and can house equipment or personnel. The main difference lies in their construction and purpose; trenches prioritize mobility and positioning, whereas bunkers focus on shelter and defense. Additionally, bunkers often have reinforced walls and ceilings, making them more resilient to direct attacks.