point – n. individual credit for a correct answer
mark – n. in British English, a letter assigned to a range of points
score – n. the result of combining points; v. to achieve or earn something such as points or a grade
grade – n. a letter assigned to a range of points
range – n. a series of numbers that includes the highest and lowest possible amounts
letter grade – n. a letter assigned to a score or a value; A = excellent, B = good, C = average and so on.