Unlike traditional bitcoin-like blockchain, where all transactions are compiled in blocks in a single blockchain, block lattice (introduced by Nano) is a collection of multiple blockchains. That’s why we also call it blocklist as that’s how exactly the Lyra node database looks like - a big list (collection in nosql database terms) of blocks. Each user account adds transactions to their own blockchain. Such design enables extremely high scalability, instant authorization and settlements, super light clients, and many other features.
Each Lyra user maintains its own blockchain called account. Each block contains a single transaction. The network does not maintain a single chain of blocks, which allows it to process transactions faster.
Lyra transaction consists of send and receive blocks. The sender's wallet app generates a send block and sends it to the authorizer nodes for authorization. Once a send block is authorized by the quorum of authorizers, it is added to the sender account’s blockchain.
When a recipient receives the broadcasted authorized send block, it generates the receive block and sends it to the authorizers for authorization. Once authorized, the receive block is added to the recipient account’s blockchain (which is also a part of chain collection).
Compared to traditional payment processing flow, send block processing is similar to authorization phase, while receive block corresponds to the settlement phase of the payment transaction processing. However, once a send block is accepted by the network, Lyra transaction is considered irreversible, even before the receive block is created by the recipient.