Gemini 2.0 Flash and GPT-4o solve different problems. Flash is Google's speed-and-cost tier — very low latency, a large context window, and native multimodal input that make it ideal for high-volume tasks like classification, extraction, and RAG answer generation, where you process huge numbers of requests and cost per token matters most.
GPT-4o is the more capable all-rounder, with stronger reasoning, writing, and tool use across a broad range of tasks, plus OpenAI's larger ecosystem. The trade-off is cost and latency at scale. For most everyday assistant work GPT-4o is the safer pick; for bulk pipelines where throughput and price dominate, Flash wins comfortably.