EVM vs. SVM: Client Differences

Types of validator clients

As Ethereum transitioned from PoW (Proof of Work) to PoS (Proof of Stake), it adopted two types of validator clients: Execution Layer (EL) and Consensus Layer (CL) clients. Execution clients are responsible for receiving new transactions broadcasted on the network, executing them on the EVM, and maintaining the current state and database of all Ethereum data. Consensus clients, on the other hand, implement the consensus algorithm of PoS and achieve consensus on the network based on verified data from execution clients. These two types of clients serve different roles, which is why Ethereum validator nodes typically run both execution and consensus clients. In contrast, Solana combines both functionalities in a single client.

Here is the list of execution clients for Ethereum:

Number of nodes in Ethereum and Solana

For Ethereum, you can check the number of nodes operated for each validator client by visiting clientdiversity. For Solana, you can find this information from the Validator Health Report.

Types of node

Nodes come in various forms depending on their use cases and required conditions. They can range from heavyweight nodes that store all data to lightweight nodes focused solely on processing transactions.

Ethereum classifies nodes into three types based on the scope of data storage and participation in consensus:

• Full Node: Full nodes validate the blockchain block by block, downloading and verifying the data for each block. There are various types of full nodes, with some starting from the genesis block and validating all blocks in the entire blockchain history. Others begin validation from recent trusted blocks, typically maintaining a local copy of the most recent 128 blocks and periodically deleting older data to save disk space. Older data can be regenerated when needed.
• Archive Node: Archive nodes verify and preserve all blocks from the genesis block onward, never deleting any data. They are essential for services like block explorers, wallet providers, and chain analysis, as well as for querying test sets without mining them reliably.
• Light Node: Light nodes download only block headers instead of the entire blockchain. Additional information required by light nodes is requested from full nodes. Light nodes can independently verify data received against the state root of block headers. They do not require high bandwidth or powerful hardware, making it possible to participate in the Ethereum network from mobile phones or embedded devices. Light nodes do not participate in consensus, meaning they cannot become miners or validators, but they provide the same functionality and security guarantees as full nodes, allowing access to the Ethereum blockchain.

For Solana, nodes are divided into two types based on their participation in consensus:

• Consensus Nodes: Consensus nodes play a vital role in the network by creating and proposing new blocks to the network and voting on the validity of new blocks proposed by other nodes. They are central to the network's functioning.
• RPC Nodes (Remote Procedure Call Nodes): RPC nodes are essential for dApps built on top of the Solana blockchain, serving as gateways for blockchain data. Like consensus nodes, they independently verify all new blocks and network changes but do not participate in voting.

Solana distinguishes RPC nodes from consensus nodes from the start. However, RPC nodes do not participate in voting. Ethereum's RPC nodes are typically based on full nodes or archive nodes.

Why does Solana categorize nodes this way? Unlike Ethereum, Solana generates a high number of transactions per second, and storing the entire blockchain on every node is impractical due to the high transaction volume. Currently, Solana stores data using Google Bigtable, and RPC nodes access data from there. Therefore, Solana focuses less on storing a large amount of data locally, which differs from Ethereum's node categorization criteria.

In summary, here's a comparison:

List of RPC services

There are RPC services that support both Ethereum and Solana simultaneously, as well as those that support a single chain. Services like Alchemy and Quicknode support both Ethereum and Solana. You can check Solana's various RPC services here.