(10) Why would someone use cassandra over hbase? - Quora

(10) Why would someone use cassandra over hbase? - Quora

To me the biggest difference is in their consistency models. Cassandra's consistency model is based on Amazon's Dynamo: it provides eventual consistency. This is very appealing for some applications where you want to guarantee the availability of writes. Similarly, Cassandra tends to provide very good write scaling. The tradeoff is that if you want consistent reads, you have to read from a majority of the copies of data, which is inherently slower and does not scale as well. For this reason many users employ a caching layer to accelerate reads.

Read full article from (10) Why would someone use cassandra over hbase? - Quora