Terraform is very good when it comes to declaring topologies: “there should be N items of this type, in this network, with these characteristics”. It remembers state; as you add or remove stuff to your topology, it will take care of doing all the necessary work to go from topology A to topology B, and detect any inconsistency.

I don’t know Ansible much, but I believe it’s more of a procedure-oriented system, where you declare the steps necessary to reach A, then again to go from A to B. This can be an issue if any item is actually not in the state you expected.