There is no difference in meaning between playwright and dramatist although, historically, some people who wrote plays preferred the term dramatist because playwright classes them with skilled laborers such as wheelwrights while dramatist sounds more prestigeous.
Sartre
Shakespeare is the best-known dramatist in the world, without question. Therefore the answer must be "none".
Playwright
There have been several.
A dramatist means a person who writes plays or you could say drama
Do you mean the quality of Quince as a person or as a dramatist or as a carpenter? He's a pretty good person, an awful dramatist, and as a carpenter, well, nobody knows.
William Cartwright - dramatist - was born in 1611.
Thomas Arthur - dramatist - died in 1532.
John Day - dramatist - was born in 1574.
James Kenney - dramatist - was born in 1780.
David Eldridge - dramatist - was born in 1973.
Terry Johnson - dramatist - was born in 1955.
David Greig - dramatist - was born in 1969.
George Fisher - dramatist - died in 1970.
George Fisher - dramatist - was born in 1909.
John Ford - dramatist - was born in 1586.