Flux 1 Schnell is Black Forest Labs' speed-optimized variant of their Flux model family. "Schnell" means "fast" in German, and the model delivers exactly that—sub-second generation at the lowest cost tier. It uses a distilled architecture that prioritizes throughput over maximum fidelity, making it ideal for rapid exploration and high-volume workflows.
GLM Image comes from Zhipu AI, a Chinese AI research company known for their GLM (General Language Model) family. Built on their GLM-4 foundation, this image generation model was designed with strong text rendering capabilities—a common weakness in other diffusion models. At roughly 15x the cost of Schnell, it's positioned as a premium option for work requiring accurate typography.
The fundamental difference lies in their specializations. Schnell trades quality for speed, while GLM Image focuses on text accuracy and overall image coherence. Where Schnell might struggle to render a readable "OPEN" sign on a storefront, GLM Image tends to produce clear, legible text that integrates naturally into the scene.
At roughly 15x the cost per image, the choice depends heavily on your use case. If you need text in your images—signs, labels, titles, or any typography—GLM Image's accuracy often means fewer regenerations. For pure visual exploration without text, Schnell's volume advantage becomes more compelling.
Tip: GLM Image supports batch generation of up to 4 images per request. When exploring variations, this can be more efficient than generating one at a time, even accounting for the higher per-image cost.