The key difference between RDBMS and DBMS is the way that the various files that will be placed will be stored. In RDBMS, you can expect that the data will be in tabular form. In DBMS, you can expect that the data will be stored as various files. You also cannot expect that there will be connections between the various files that will be stored.
If in case you are wondering which one is more advanced, the RDBMS is considered to be the more advanced version of the RDBMS. They both have various functions that can make storing data easier. It will be easy to create and maintain data so that the right and proper data can be extracted and also saved.
DBMS means Data Base Management System, and RDBMS means Relational Database Management System. DBMS applications will usually store the different data that you have in files while RDBMS will store your data in a sort of tabular form. Usually, in DBMS, it will be easier for you to determine the connection and the relationship between the various data that will be placed. In RDBMS, there is a need to have a primary key.
The primary key will be the main connection of the various data and files that will be available in tabular form. Some will say that the RDBMS seems to be the extension of the DBMS. Just take note that one main difference is that RDBMS would need to make sure that all of the details are relational, but in DBMS, this is not required.