What is DataBase（DB）?
a place for save datas, like a storehouse.
What is DataBase Management System(DBMS)?
Database Management Systems (DBMS) are software systems used to store, retrieve, and run queries on data. A DBMS serves as an interface between an end-user and a database, allowing users to create, read, update, and delete data in the database.
Mysql,MangoDB or Oracle they all DBMS.
https://www.appdynamics.com/topics/database-management-systems