Sidechains vs lightning

"Layer 2" is used loosely; the trust models differ sharply. A sidechain (e.g., Liquid) is a separate blockchain with its own asset pegged to BTC: coins move in by locking BTC with a custodial federation (a threshold multisig of "functionaries"), which issues equivalent sidechain tokens (L-BTC) and must cooperate to redeem them. Security rests on the federation's honesty quorum, not on Bitcoin's proof-of-work. Lightning, by contrast, keeps funds in bilateral Bitcoin contracts either party can unilaterally enforce on-chain — no federation, no separate asset.

Nuance: Neither model is strictly better: sidechains offer features Bitcoin script cannot (confidential amounts, asset issuance, faster blocks) at the cost of federation trust; Lightning is trust-minimized but constrained to payments within channel liquidity. Precision matters on stage: calling Liquid "Bitcoin with extra features" or Lightning "a sidechain" both misstate custody.

Common misstatements:

• "L-BTC is bitcoin." — It is a federation-backed claim on bitcoin; redemption depends on the functionary quorum.
• "Sidechains inherit Bitcoin's security." — Federated sidechains inherit none of Bitcoin's PoW security; they have their own consensus and custody assumptions.
• "Lightning and Liquid are both Layer 2s, so they're equivalent." — Unilateral-exit enforceability against the base chain is the distinguishing property; Lightning has it, federated sidechains do not.