title: understanding Kafka end offset and committed offset
body: <p>I want to fetch Kafka topic's committed offset and end offset (position) using Pyhon and Kafka client, </p>
  
  <p>and I'm wondering why the offset is received by topic + consumer-group itself (<code>KafkaAdminClient.list_consumer_group_offsets(consumer_group)</code>) </p>
  
  <p>while the position is received by a consumer + topic's partitioned (<code>KafkaConsumer.end_offsets(partitions)</code>).</p>
  
  <p>Does anyone have a clue?</p>