Drop - Dropping a course means removing a course from your schedule before the add/drop deadline. Dropping a course will not appear on your transcript and will not affect your GPA.
Withdrawal - Withdrawing from a course means removing a course from your schedule after the add/drop deadline. Withdrawing from a course will appear on your transcript with a grade of "W".
It is important to note that the specific deadlines and policies for dropping and withdrawing from courses vary from school to school and program to program.