Spring Kafka Partitioning

What is the difference in the behavior of the below two code snippets to publish a message?

Approach 1

Message<String> message = MessageBuilder.withPayload("testmsg")
        .setHeader(KafkaHeaders.MESSAGE_KEY, "key").setHeader(KafkaHeaders.TOPIC, "test").build();

ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(message);

Approach 2

ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send("test", "testmsg");

Topic Config:

$ bin/kafka-topics.sh --describe --zookeeper localhost:2181 --topic test
Topic:test   PartitionCount:3    ReplicationFactor:1 Configs:
Topic: test  Partition: 0    Leader: 0   Replicas: 0 Isr: 0
Topic: test  Partition: 1    Leader: 0   Replicas: 0 Isr: 0
Topic: test  Partition: 2    Leader: 0   Replicas: 0 Isr: 0

Observation:

If there are 3 consumers, one per partition; Approach 1 leads to all messages consumed by a single consumer from a single partition. With Approach 2; consumption is equally split between the 3 partitions/consumers.