PL/SQL is procedural language where s SQL is data oriented language.
PL/SQL purpose is to create applications but SQL is data manipulator and reviewer
PL/SQL executions works at block of code level while SQL execution is per statement at a time.
PL/SQL servers for building, formatting and display application screens but SQL sources data for that screens.
PL/SQL is procedural based and instructs database on how to do but SQL is declarative level which helps database on what to do.
PL/SQL purpose it to code program blocks, procedures, triggers, functions, and packages but SQL is used to code queries, DCL, DML and DDL statements
SQL can be subset of PL/SQL but PL/SQL can not be subset of SQL