As the base level of blockchain architecture, a layer-1 blockchain validates and executes transactions independently of other blockchain networks. Bitcoin, Ethereum, and Solana are examples of layer-1 blockchains.

Layer-2 blockchains extend the capabilities of the layer-1 network by enhancing transaction throughput and reducing gas fees while inheriting the base network's security (layer-1 network). Ethereum has several popular layer-2 networks, such as Arbitrum, Base, and Optimism.

Comparison

https://www.investopedia.com/what-are-layer-1-and-layer-2-blockchain-scaling-solutions-7104877

https://www.gemini.com/cryptopedia/blockchain-layer-2-network-layer-1-network

https://academy.binance.com/en/articles/blockchain-layer-1-vs-layer-2-scaling-solutions

L1 https://www.moonpay.com/learn/blockchain/layer-1-blockchain

L2

https://www.coinbase.com/learn/crypto-basics/what-are-ethereum-layer-2-blockchains-and-how-do-they-work

https://www.ledger.com/academy/topics/blockchain/what-are-ethereum-layer-2-blockchains-and-how-do-they-work