Key differences. Antithesis is a rhetorical device used in writing and speech to present contrasting ideas in a way that emphasizes their differences. An oxymoron is a figure of speech that combines two contradictory terms, creating a paradoxical effect. On the other hand, antithesis is a rhetorical device that juxtaposes contrasting ideas, often in a parallel structure, to highlight their differences. 5. An oxymoron is a compact paradox that brings together two opposite terms, an antithesis. While antithesis aims to accentuate differences for rhetorical impact, juxtaposition seeks to create visual or thematic contrasts to deepen understanding or evoke emotions. Understanding these distinctions gives writers versatile tools to enrich their prose and engage readers effectively. Appearance. Antithesis.