What is the difference between THETA and THETA fuel?

Could you elaborate on the fundamental differences between THETA and THETA Fuel in the realm of cryptocurrency? As I understand, both play a crucial role in the Theta Network, but I'm curious about their specific functionalities and how they differ. For instance, does THETA represent ownership or staking rights, while THETA Fuel serves as the transactional currency? Additionally, how do their supply mechanisms and use cases vary? I'd appreciate a concise yet comprehensive overview of these distinctions to gain a clearer understanding of their respective roles within the Theta ecosystem.