1. Consensus Mechanism: Ethereum uses a proof-of-work consensus mechanism, similar to Bitcoin, where miners compete to solve complex mathematical puzzles to validate transactions. On the other hand, NEM utilizes a proof-of-importance algorithm that takes into account factors like account balance and transaction history to determine who can add a new block to the blockchain, offering a more energy-efficient and resource-friendly approach.

2. Smart Contracts: Ethereum is well-known for its ability to create and execute smart contracts, self-executing contracts with the terms of the agreement between buyer and seller being directly written into code. NEM also supports smart contracts but with a different approach, using a feature called "smart assets" which allows users to create customizable and secure digital assets without the need for smart contract development.

3. Scalability: Ethereum has faced challenges with scalability due to its design limitations, leading to network congestion and high fees during peak usage. NEM, on the other hand, has implemented a unique feature called the "Apostille system" which allows for efficient and scalable transfer of assets and data, improving the overall performance of the blockchain network.

4. Privacy and Security: Ethereum transactions are public and transparent, allowing anyone to view the details of a transaction using the blockchain explorer. NEM offers enhanced privacy and security features through its advanced encryption techniques, providing users with the option to send and receive private transactions that cannot be viewed by unauthorized parties.

5. Governance Model: Ethereum operates as a decentralized network without a formal governance structure, relying on community consensus for decision-making. In contrast, NEM has a more structured governance model with designated entities like the NEM Foundation that oversee the development and direction of the platform, ensuring a more organized approach to decision-making and development.

6. Community and Ecosystem: Ethereum has a larger and more established community compared to NEM, with a wide range of developers and projects built on its platform. NEM, while growing steadily, has a smaller community but is known for its strong partnerships with industry players and government entities, showcasing a different approach to building a supportive ecosystem.

In Summary, Ethereum and NEM differ in their consensus mechanisms, approach to smart contracts, scalability solutions, privacy and security features, governance models, and community ecosystems.