Pulsar can have both MQ semantics and pub/sub semantics. In pub/sub it's sorta like "Kafka with all bits people found it necessary to build later already built

Pulsar can have both MQ semantics and pub/sub semantics. In pub/sub it's sorta like "Kafka with all bits people found it necessary to build later already built in", e.g., a proxy, schema registry, connectors, replication, tiered storage, all out of the box. It also has lightweight streaming functions built-in, but they operate per record, so good for lightweight transforms/routing, not for stream aggregations etc. It has more moving parts also, brokers are decoupled from storage, which is handled by BookKeeper, and replication between two clusters requires a ZooKeeper that both clusters can access, in addition to the ZK used by the brokers and bookies. And it's a reasonably new project, so last time I looked into it, some of the documentation was incorrect, especially around managing bookies.