What is the difference between SQL and PL/SQL?

SQL is mainly a query language that permits you to create a single query or execute a single update / delete / insert in your code. PL/SQL, on the other hand, is a programming language used in Oracle (hence the "PL" term). PL/SQL allows you to code a full functioning program while creating more than just a single update / delete / insert / select statement.

So, all in all, SQL is executed in one statement at a time; whereas, PL/SQL is executed as a block of code. We can embed or include SQL in a PL/SQL program; but, not vice versa.