Kafka
Kafka is used in real-time streaming data architectures for providing real-time analytics.
Kafka is a scalable, durable, fast and fault tolerant publish-subsribe messaging system
Kafka has higher throughput, replication and reliability characteristics.
Kafka can be used as an input plugin
Kafka can work with Spark Streaming, Flume/Flafka, Storm, Flink, HBase and Spark
Kafka is powerful than Logstash.
Logstash
Logstash is an open-source, data processing pipeline that allows to collect data from a number of resources, transform it and send it on the desired location
Logstash is a tool to collect, process and forward events and log messages.
It has pre-built filters to transform common data-types, indexing them in elastic-search and start querying without building the custom data transformation pipelines
It has flexible plugin architecture with over 200 plugins available on Github. You can also create one if none suits your requirements.
