#ETH

The real difference between Ethereum's Layer 2 (L2) and execution sharding.

1. **Technical similarities**: Vitalik pointed out that from a technical perspective, both L1 sharding and the rollup-centric world require a lot of computation and data bandwidth when processing a large number of transactions. Both use ZK-SNARKs to verify computations and data availability sampling (DAS) to verify data availability.

2. **Diversity of execution environments**: Ethereum L2 provides a diversity of execution environments, allowing different "zones" to have different account working rules, virtual machine working methods, and other characteristics. This enables some methods that are difficult to achieve when Ethereum does all the work independently.

3. **Security trade-off**: L1 provides very strong security guarantees, but this also means high costs. L2 allows different security models, for example, for non-financial applications, lower security standards can be accepted, thereby reducing costs.

4. **Different use cases, different L2 types**: Depending on the security needs and scale requirements of the application, different types of L2 can be selected, such as rollups or validiums.

5. **Transaction speed**: Ethereum L1 has a block generation rate of one block every 12 seconds, while many L2s are exploring faster block times to provide higher transaction speeds.

6. **Pre-confirmation mechanism**: To provide higher speeds, L2 relies on a pre-confirmation mechanism, in which L2's validators commit to include transactions at a specific time.

7. **Organizational and cultural advantages**: L2-centric ecosystems allow builders the freedom to independently build sub-ecosystems with unique characteristics while still being part of the larger Ethereum ecosystem.

8. **Challenges facing L2**: A key challenge facing the L2-centric approach is coordination, which needs to maintain a sense of Ethereum as a whole and have network effects.

9. **Cross-L2 infrastructure**: The ecosystem needs to more fully recognize the importance of cross-L2 infrastructure, which should be valued and funded like L1 clients, development tools, and programming languages.

10. **Conclusion**: Although L2 and sharding are often described as two opposing blockchain expansion strategies, in fact their underlying expansion methods are the same. The main difference is who is responsible for building and updating these parts, and how much autonomy they have.