What distinguishes the hydrologic cycle on Titan from the water-based cycle on Earth?

It involves the circulation and precipitation of liquid methane and ethane.

Titan possesses a remarkably unique environment characterized by an active hydrologic cycle that operates differently from Earth's. Instead of water, the cycle on Titan is driven by liquid hydrocarbons, specifically methane and ethane. These substances condense and rain down onto the surface, forming extensive river systems, lakes, and vast seas. This process mimics the patterns of Earth's own water cycle, such as evaporation and precipitation, but the chemical composition is entirely based on organic petrochemicals, making it a natural laboratory for studying complex organic chemistry under conditions that are drastically different from our own planet.