Describe the differences inmeaning between the terms relation and relation schema. Illustrate your answer by referring to your solution to Exercise below.

Student (student-id, name, program)

Course (courseno, title, syllabus, credits)

Course-offering (courseno, secno, year, semester, time, room)

Instructor (instructor-id, name, dept, title)

Enrols (student-id, courseno, secno, semester, year, grade)

Teaches (courseno, secno, semester, year, instructor-id)

Requires (maincourse, prerequisite)