According to ByteDance's internal evaluation benchmark MagicBench, Seedream 4.0 outperforms Nano Banana for stronger performance in prompt adherence, alignment, and aesthestics. It can produce images with higher quality (up to 4K resolution), batch processing, and more creative and artistic transformations. However, Nano Banana focuses more on realistic edits and doesn't support multiple images in a single batch. After several edits, there might be a drop in resolution compared to the original source, which might not appear in Seedream 4.0.