The big difference is that it's a much easier problem to solve in the context of a log (see Paxos, Raft, ZAB, et al), where the consensus membership is more or

The big difference is that it's a much easier problem to solve in the context of a log (see Paxos, Raft, ZAB, et al), where the consensus membership is more or less fixed, as opposed to having to manage it among an adhoc membership set.