blockchain – What is the difference between Consensus and Distributed Consensus?

This is more of a clarification than as a question. Since I didn’t have the rep to post a comment in this question, I’m putting this itself as a question.

Sources I’ve referred till now:

A fundamental problem in distributed computing and multi-agent systems is to achieve overall system reliability in the presence of a number of faulty processes. -Wikipedia

It explicitly indicates that consensus is a fundamental problem in Distributed Systems.

However,

“Consensus” means when everyone is on the same page. -Bitcoin SE.

My understanding till now is that if every node had one vote, then for the whole network of nodes to agree on a decision, use of consensus is required. If the system at hand is not distributed, then the environment reduces to just one node which doesn’t need consensus mechanism at all to come to a decision. So my confusion is, are there any situations where consensus is required even when the system is not distributed?

If yes, please explain what’s the difference between the terms “Consensus” and “Distributed Consensus”. If possible, present an example.

If no, does that mean the terms are the same?