SQL is a standardized query language used for relational databases. PL/SQL is a procedural language that implements SQL codes in an improvised manner. At a time, SQL can execute only a single operation, whereas PL/SQL permits group operations in a block. SQL does not support variables and control structures. But PL/SQL supports variables and data types and control structures like for loop, if-else, while loop, etc. PL/SQL can be used to develop web-based applications and server pages, whereas SQL is only used to retrieve data and modify table structure and data. SQL can be embedded into PL/SQL code, but the reverse is not possible.