Not every system called a blockchain works the same way, so each iKnow Blockchain profile states a system class before comparing anything else. A blockchain L1 orders transactions into blocks under its own consensus and fork choice. A rollup L2 executes elsewhere but posts its data or proofs to an L1, so its safety leans on that L1 plus its own proof and upgrade system. A sidechain has its own validators and is only joined to another chain by a bridge, so it does not inherit that chain's security. A non-block ledger reaches agreement without miners or stakers competing to add blocks, for example through a directed graph of gossiped events or through voting rounds among trusted validators, so block-based measures such as block time, orphan rate or reorg depth may not apply.
Key idea. Before comparing speed, fees or security, ask where the final record lives and whose agreement makes it final: its own validators, a parent chain, a bridge committee or a trusted validator list.
Example
A rollup and a sidechain can both advertise low fees and compatibility with the same virtual machine, but only the rollup posts its transaction data back to its L1; the sidechain's users rely on its own validator set and its bridge.
Keep in mind
- System class is an editorial classification of cited design documents; hybrid designs carry a note explaining the choice.
- Where a dimension does not fit a system class, the profile marks it as not applicable rather than forcing a value.
- A system class says nothing by itself about quality, adoption or decentralization.
Sources
- Sidechains (ethereum.org developer docs) (external site)
- Scaling (ethereum.org developer docs) (external site)
- Consensus Protocol (XRP Ledger docs) (external site)
- Hashgraph Consensus Algorithm (Hedera docs) (external site)