BS. They have quite different meanings.

- "Aristos" means "the best", usually indicating the nobility (best by birth).

- "Meritus" means deserved or deserving, indicating what one really does in life, not his status.

In an aristocracy, the peasant will stay a peasant.

In a meritocracy, a smart and resourceful peasant has a fair chance to ascend the social ladder (e.g. that happened to LOTS of people in the USA).

Therefore, Buffy's claim is born out of ignorance or, more likely, of ideology: the need to deny or smear real meritocracy.