How Do Different Blockchain Architectures (E.g. DAGs) Handle Transaction Confirmation and Finality?

Traditional blockchains use linear chains where confirmation relies on depth. Directed Acyclic Graphs (DAGs) like IOTA or Nano, however, do not have blocks or a single chain.

Instead, transactions confirm other transactions, forming a graph structure. Finality is achieved through a different mechanism, often a voting or consensus process among nodes on the transaction's validity and placement within the graph.

This can lead to near-instantaneous probabilistic finality, but they face their own unique attack vectors.