If they were opposite then they would be an oxymoron but, they are the same so, I would say a redundancy.
opposite meanings.
I guess you could claim one opposite of a tautology is an oxymoron.
The term is an oxymoron, which pairs apparently contradictory terms to create a specific, often poetic meaning. Examples include deafening silence, hated affection, or mercy killing.
No, an oxymoron is two words together that mean completely opposite things like big shrimp, pretty ugly, or thinly spread.