Is Avalanche on the Ethereum network?

Could you please clarify for me if Avalanche operates within the Ethereum network? I've been hearing a lot about Avalanche's unique consensus mechanism and scalability features, but I'm not entirely sure if it's a part of the Ethereum ecosystem. Could you enlighten me on this matter? If Avalanche isn't on Ethereum, could you also explain the differences between their architectures and functionalities? It would be greatly appreciated if you could provide a concise yet informative answer to help me understand this better. Thank you in advance for your assistance.