RDBMS is a super set of DBMS plus some more features.

Consolidated few differences here.

	DBMS	RDBMS
Organization, storage, management, and retrieval of data	Yes	Yes
Flat file design	Yes	No
Relational design	No	Yes
Password protection	Yes	Yes
Enforce referential integrity	No	Yes
Null or blank data management	Yes	Yes
Meta data support	Yes	Yes
Support relatively large set of data	No	Yes
Support complex business applications	No	Yes

Microsoft Access is an example of  DBMS.

Oracle, Microsoft SQL Server, DB2 are few examples for RDBMS.