The SQL standard defines users and roles as separate concepts, and they are created with the SQL commands CREATE USER and CREATE ROLE, respectively. A user is a user to connect to a database, and a role is a collection of different privileges. Users can be granted different privileges individually, or they can be granted privileges in bulk by granting roles.
PostgreSQL includes the concepts of users and roles, but they are internally implemented as exactly the same thing. Executing the CREATE USER command internally invokes the CREATE ROLE command. The only difference is that the LOGIN attribute defaults to NOLOGIN if CREATE ROLE is used, and it defaults to LOGIN if CREATE USER is used. That means users can connect to the database by default, but roles cannot.
Both CREATE ROLE and CREATE USER require CREATEROLE or superuser privilege.
Internally, both users and roles are the same, so both can be granted to other users or roles via GRANT.
PostgreSQL schemas must be created separately by running CREATE SCHEMA, and are not created automatically, for example by CREATE USER.
PostgreSQL provides a utility command called createuser to create database users from the OS command line. Internally it executes CREATE ROLE, but by default it creates a user with LOGIN privileges, so in that sense it is equivalent to CREATE USER. No command called createrole is provided, but you can create a NOLOGIN user by executing with the option -L or --no-login.


So the correct answers are C and E.