e72bfd15_Cassandra_vs_HBase___WhyNosql__Cassandra
[HBase] Uses binary keys. It's common to combine three different items together to form a key. This means you can search by more than one key in a give table. [Cassandra] 
Uses string keys. Very common to use uuids as the keys. You can use TimeUUID if you want your data to be sorted by time.
Cassandra vs HBase | WhyNosql
Cassandra