What is the difference between DBMS and RDBMS?

Question

After reading some answers on different websites I am confused now. So, it would be helpful to mention the key difference between DBMS and RDBMS and any relation between the

Answer 1

There are other database systems, such as document stores, key value stores, columnar stores, object oriented databases. These are databases too but they are not based on relations (relational theory) ie they are not relational database systems.

So there are lot of differences. Database management system is the name for all databases.