If we replace TN with Broker and vice versa. Will it work? What additional functionalities TN provides?
You cannot compare TN vs Broker and each has its own capabilities…ofcourse you can have TN with out Broker and Broker with out TN. It’s all depends on your architecture/design needs how you want to route messages dynamically having with more visibility
Please review all the TN and Broker user guides/concepts/facts for more details via SAG documentation online.
Broker gives highly performance (dealing with pub-sub queues/JMS P2P messages) to your IS messaging layer one publish and multiple suscribers (canonical/Internal documents).
TN gives more of UI/Visibility/eTransactional details/metrics/external partners connections (hub/spoke methodology)