Cruise missiles are big missiles that carry large payloads to hit ground targets or to badly damage/sink ships. Ballistic missiles look similar, but they keep the engine off and don't stay at a lower height to be more accurate like cruise missiles do. Instead, they go high up to the edge of space and turn off the engine. Since there's no air friction in space, they don't need the engine on to continue moving forward at the same speed. They then crash into the target from the sky. The Topol M is the missile in the picture and is a ballistic missile. In short, cruise missiles have an engine always running and fly low through the atmosphere to get to a target. Ballistic missiles go to the edge of space and turn off their engine to fall to a target. You could say cruise missiles fly while ballistic missiles fall. 