$ADA

Ethereum: Currently uses Proof-of-Stake (PoS) via the Ethereum 2.0 upgrade.

Cardano: Built from inception with Ouroboros PoS, which is peer-reviewed and energy-efficient.

Cardano claims Ouroboros is more secure and formally verified. Ethereum has greater validator participation and network activity.

Ethereum: Uses Solidity, widely adopted with a large developer community.