SQS is fantastic at exceptionally high total volumes of messages - you probably can't saturate it. But it's not great for streaming a list of ordered messages. SQS has a FIFO mode but performance will never be what you can get out of Kafka.

Also, SQS isn't pub/sub. Kafka and SQS really have very different use cases.

Agreed, I was just trying to answer the parent's question as to what it is.