The security of off-chain BTC is not uniform—counterparty risk increases in the following order: Lightning-Channel BTC → Ark BTC → Spark BTC → Liquid BTC → Cashu BTC → Custodial BTC. The Lightning Network is a channel layer plus a routing layer. If you run your own channel, the routing layer lets you settle payments directly. For the other five off-chain wallets, the operator shares its own Lightning channels with users, allowing them to send and receive Lightning payments. Liquid example • Paying — your wallet sends the same amount of L-BTC, and the operator pays the invoice through its channels. • Receiving — the operator first receives BTC over Lightning, then sends you the equivalent L-BTC. Liquid, Spark, and Ark can make users’ sending and receiving of Lightning payments atomic. Lightning is the transport network—other off-chain solutions plug in as special nodes.