title: Apache Solr which version to download 3.6.2 or 4.0, what is the main difference
body: <p>There are 2 versions of Apache Solr on their official website 3.6.2 and 4.0: </p>
  
  <p><a href="http://lucene.apache.org/solr/downloads.html" rel="nofollow">http://lucene.apache.org/solr/downloads.html</a></p>
  
  <p>What is the main difference, how to choose one? </p>