Hy4 preview vs Seedream 4.5: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of Hy4 preview and Seedream 4.5 — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
Hy4 preview
Tencent
Tencent's open-weight Hy4 preview, a 770B-parameter Mixture-of-Experts model with 49B active parameters and a 1M-token context window.
Key features
- 770B Mixture-of-Experts Architecture: Holds 770 billion total parameters while activating only 49 billion per token, so capacity scales without proportional inference cost.
- 1M-Token Context Window: Accepts inputs exceeding one million tokens, allowing whole codebases, long document sets or extended agent traces in a single prompt.
- Apache 2.0 Open Weights: Released under a permissive licence that allows commercial use, modification and redistribution with no separate agreement.
- Productivity Task Focus: Tuned for real-world coding, office work and scientific research rather than narrow benchmark optimisation.
- Multi-Product Availability: Accessible globally through Tencent's WorkBuddy, CodeBuddy, Yuanbao and ima applications in addition to the raw weights.
- API Access via TokenHub and OpenRouter: Can be called through Tencent Cloud TokenHub or OpenRouter for teams that prefer hosted inference over self-hosting.
Best for
- Whole-Repository Code Work: Load an entire codebase into the million-token context to reason about refactors and cross-file dependencies at once.
- Long-Horizon Agent Tasks: Drive multi-step agent workflows where the full history of tool calls and intermediate results must stay in context.
- Self-Hosted Deployment: Run a frontier-scale open-weight model on private infrastructure where data cannot leave the organisation.
- Scientific Literature Analysis: Ingest large collections of papers or experimental logs and synthesise findings without chunking the input.
- Office Document Processing: Summarise, draft and restructure long reports, contracts and spreadsheets in enterprise workflows.
- Commercial Fine-Tuning: Adapt the weights for a proprietary product under the Apache 2.0 licence without negotiating a model licence.
Seedream 4.5
ByteDance Seed (ByteDance)
A high-fidelity image generation model from ByteDance focused on production-ready, high-resolution and batch-consistent image synthesis.
Key features
- High-Fidelity Image Generation: Produces high-resolution images with strong detail and visual fidelity suitable for print, catalogs, and other production outputs, aiming to reduce manual retouching.
- Batch Consistency: Generates consistent visual style and composition across large batches of images, enabling scalable asset pipelines and catalog production with predictable results.
- Enhanced Text Rendering: Improved handling and rendering of in-image text and infographics to increase readability and structural correctness within generated images.
- Bilingual Prompt Understanding: Builds on Seedream lineage to accept and accurately interpret prompts in both Chinese and English, supporting bilingual creative workflows.
- RLHF-Based Alignment: Trained and fine-tuned using RLHF iterations to better align outputs with human preferences, improving prompt-following and aesthetic choices.
- Pipeline & Endpoint Integration: Deployable through model service endpoints (e.g., via provider platforms like Volcano Engine) to integrate into automated content production pipelines and MCP servers.
- Instruction-Based Editing Adaptation: Can be adapted for instruction-driven image editing tasks, allowing targeted modifications based on textual directions.
- High-quality text-to-image generation (demonstrated for Seedream 2.0/3.0 families)
- Native Chinese-English bilingual prompt and text rendering support
- Optimized via RLHF for improved alignment with human preferences and ELO scoring
- Instruction-based image editing and adaptation capabilities
- Integration with a bilingual large language model as a text encoder for richer prompt understanding
- Can be deployed as a hosted inference service (inference endpoints, API keys) on platforms like Volcano Engine/Doubao
- Example MCP server integration using FastMCP framework for serving Doubao (doubao-seedream-3.0-t2i)
- Supports programmatic inference via created endpoints and API keys; server examples use uvx for direct execution
Best for
- High-Resolution Batch Production: Generating consistent, print-ready product images and catalog assets at scale for e-commerce and retail catalogs.
- Marketing Creative Generation: Producing campaign visuals, ad creatives, and variations with consistent brand style for marketing teams.
- Infographic and Text-Rich Assets: Creating visuals that include readable, well-placed text for reports, posters, and social graphics.
- Instruction-Based Image Editing: Applying targeted edits to existing images using textual instructions for iterative creative workflows.
- Pipeline Integration for Agencies: Embedding the model into automated pipelines or MCP servers to provide on-demand generation via API endpoints for studios and enterprises.
- Design Asset Exploration: Rapidly generating concept art, moodboards, and multiple variations for designers to iterate on visual directions.
- Text-to-image generation for bilingual (Chinese/English) marketing and creative content
- Instruction-driven image editing (e.g., modify images via text instructions)
- Integration into image-generation services via hosted inference endpoints and API keys
- Research and benchmarking for prompt-following, aesthetics, and text rendering
- Embedding in MCP servers or microservice architectures to provide image generation APIs