The main differences between RDBMS and HBase data model are as follows:
1. Schema: In RDBMS, there is a schema of tables, columns etc. In HBASE, there is no schema.
2. Normalization: RDBMS data model is normalized as per the rule of Relation DB normalization.
HBase data model does not require any normalization.
3. Partition: In RDBMS we can choose to do partitioning. In HBase, partitioning happens automatically.