$ETH Ethereum and Bitcoin differ significantly in efficiency due to their underlying technologies and intended use cases.

- **Consensus Mechanism**: Bitcoin relies on **Proof-of-Work (PoW)**, which is energy-intensive and slower. Ethereum transitioned to **Proof-of-Stake (PoS)**, reducing energy consumption by over 99% and improving transaction efficiency.

- **Transaction Speed**: Bitcoin processes around **7 transactions per second (TPS)**, while Ethereum can handle **up to 30 TPS**. Layer 2 solutions like **Optimism and Arbitrum** further enhance Ethereum’s scalability.

- **Smart Contracts & Utility**: Ethereum supports **decentralized applications (dApps)** and **smart contracts**, making it more versatile. Bitcoin primarily serves as a **store of value**, limiting its efficiency in complex transactions.

- **Fees & Cost Efficiency**: Bitcoin’s transaction fees fluctuate based on network congestion. Ethereum’s **gas fees** can be high but are mitigated by Layer 2 solutions and upcoming upgrades.