grading vs marking

grading and marking both are nouns.

Word	Noun	Adjective	Verb	Adverb
grading	Yes	No	No	No
marking	Yes	No	No	No

As nouns, grading and marking are synonyms defined as:

grading and marking: evaluation of performance by assigning a grade or score

Other synonyms of grading include scoring.

grading (noun)	marking (noun)
the act of arranging in a graduated series	evaluation of performance by assigning a grade or score
evaluation of performance by assigning a grade or score	the act of making a visible mark on a surface
changing the ground level to a smooth horizontal or gently sloping surface	a pattern of marks
	a distinguishing symbol