What is the difference between leader-follower and leaderless replication?

Leader-follower: one designated leader accepts all writes; followers replicate from leader. Cons: single bottleneck for writes; leader failure requires election; lag between leader and followers means followers may be stale. Examples: MongoDB, MySQL, Redis Sentinel. Leaderless (Dynamo-style): any replica can accept writes simultaneously. Client writes to W replicas; reads from R replicas. With W +