Solr includes Admin UI console which is free for production, ES has one that's only free for development.
Solr has contributors from a lot more different companies, so grows into multiple directions at once.
If you want to compare on a technical level, you can see my presentation from the Lucene/Solr Revolution back in November: http://www.slideshare.net/arafalov/solr-vs-elasticsearch-cas...
Solr is completely free. If that's not an issue for you and you are ready to pay, then you should compare Elasticsearch to LucidWorks Fusion, not directly to Solr.
Solr includes Admin UI console which is free for production, ES has one that's only free for development.
Solr has contributors from a lot more different companies, so grows into multiple directions at once.
If you want to compare on a technical level, you can see my presentation from the Lucene/Solr Revolution back in November: http://www.slideshare.net/arafalov/solr-vs-elasticsearch-cas...
Solr is completely free. If that's not an issue for you and you are ready to pay, then you should compare Elasticsearch to LucidWorks Fusion, not directly to Solr.