difference

what is dbms and rdbms and what is the difference between two?

What security your talking about logical or Database related ?

RDBMS doesnt say it supports ACID its part of vendor design not all RDBMS support ACID.

A DBMS (Database Management System) is a set of programs that enables storing, modifying, and extracting information from a database, it also provides users to add, delete, access, modify, and analyze data stored in Database.
RDBMS (Relational Database Managment System) is a DBMS in which data is stored in tables and the relationships among the data is also stored in tables.
In DBMS Normalization process will not be present and in
RDBMS normalization process will be present to check the
database table consistency
DBMS does not help in security in data manipulation it all user/programmer responsibility to ensure the ACID PROPERTY of the database but RDBMS helps in recovery of the database in case of loss of database due to system failure or any other reason.