Model Comparison: StepFun Step 5 Preview vs. Meta Muse Spark Open
Both StepFun and Meta have recently introduced large-scale open-weight Mixture-of-Experts (MoE) models supporting extended context windows.
Reported Facts
Analysis
Comparing the two models reveals different scaling strategies within the open-weight ecosystem. Meta's Muse Spark Open operates at a higher total parameter count of 816B, whereas StepFun's Step 5 Preview reports 600B total parameters alongside a specified 27B active parameter count. Both share a 1M context window capability. No hands-on testing or independent benchmark validation was conducted.