How do layer 2s really differ from execution sharding?

Vitalik sharing his thinking about the benefits of Ethereum's approach to scaling via Layer 2 networks.

Because Ethereum is a layer-2-centric ecosystem, you are free to go independently build a sub-ecosystem that is yours with your unique features, and is at the same time a part of a greater Ethereum.

I think this approach is a great one and it is one of the many reasons I continue to be enthusiastic about Ethereum. You can imagine a collection of networks that are all interoperable as part of the Ethereum ecosystem solving a very broad and diverse set of needs. It is harder to do, and slower in the near-term, but if done right will allow for incredible capability.