Key Takeaway
Grok4 represents a major leap over Grok3.5, with a 4× larger context window, native tool use, parallel multi-agent reasoning, and expanded multimodal and memory capabilities. While Grok3.5 introduced enhanced reasoning and improved logical consistency, Grok3.5's 32K context window and DeepSearch capabilities made it a solid intermediate model. However, Grok3.5's limitations become apparent when compared to Grok4's transformative advances in scale and functionality.
Architecture & Scale
| Model | Parameters | Context Window | Multimodality | Reasoning Engine |
|---|---|---|---|---|
| Grok 3.5 | Similar to Grok 3 with optimizations | 32K tokens (Grok3.5 standard) | Text, images, voice (Grok3.5 multimodal) | Enhanced "reasoning" model with Grok3.5 improvements |
| Grok 4 | ~1.7T parameters | 128K tokens (app) 256K via API |
Text, vision, live camera + voice | Native tool invocation; multi-agent "Heavy" |
Context Window Comparison (in thousands of tokens)
Reasoning & Tool Integration
Grok 3.5 Capabilities
- Grok3.5 Chain-of-Thought ("Think") breaks tasks into substeps with improved accuracy
- Grok3.5 DeepSearch for live web + X search with enhanced relevance
- Grok3.5 generates unique answers "from scratch," reducing reliance on internet scraping
- Grok3.5's enhanced reasoning model with improved logical consistency over previous versions
- Grok3.5 offers better factual accuracy and reduced hallucinations compared to earlier models
Grok 4 Capabilities
- Native Tool Use: Model learns when to call search or code interpreter during chain-of-thought
- Grok 4 Heavy: Runs multiple reasoning agents in parallel and "compares notes" for higher reliability
- Live Search API across X, web, and news outlets
- Unprecedented reinforcement learning fine-tuning at pre-training scale
Benchmark Performance
| Benchmark | Grok 3.5 | Grok 4 (Standard) | Grok 4 Heavy |
|---|---|---|---|
| MMLU-Pro | ~75% | Tied #1 overall | — |
| AIME (Math Competition) | 52.2% | 100% | — |
| GPQA (PhD-Level Science) | 75.4% | 87% | — |
| Humanity's Last Exam | 16–25% | 25.4%/38.6% (w/tools) | 44.4% |
| HumanEval (Coding) | ~65% | ~72–75% (SWE-Bench) | — |
| ARC-AGI V2 | ~8% | 15.9% | — |
Key Benchmark Performance Comparison
Coding Capabilities
Grok 3.5 Coding
- Grok3.5 provides similar coding support as Grok 3 with enhanced accuracy
- Grok3.5 offers improved code suggestions and detailed explanations
- Grok3.5's DeepSearch-assisted fact-checking for programming queries
- Grok3.5 standard code generation capabilities with better syntax understanding
- Grok3.5 supports multiple programming languages with consistent quality
- Grok3.5's debugging assistance helps identify common coding errors
Grok 4 Coding
- "Grok 4 Code" variant optimized for IDE integration
- Cursor IDE with live file editing
- Integrated code interpreter for testing snippets
- Scores above GPT-4 on SWE-Bench (~72–75% vs. 65–70%)
Multimodal & Memory Features
| Feature | Grok 3.5 | Grok 4 |
|---|---|---|
| Vision | Grok3.5 image upload and analysis with improved accuracy | Live camera analysis in voice mode |
| Voice | Grok3.5 human-like voice option with natural intonation | Enhanced realism & responsiveness |
| Memory | Grok3.5's 32K context; early "memory reference" beta functionality | 128K app / 256K API context; cross-session memory & Google Drive integration |
| Image Editing | Grok3.5 image editing planned in roadmap | Released in-app editing tool |
| Workspaces | Grok3.5 workspaces in UI polishing stage | Full workspaces for projects |
Deployment & Access
| Access Level | Grok 3.5 | Grok 4 |
|---|---|---|
| Beta Access | Grok3.5 SuperGrok subscribers only; early private preview access | — |
| Standard Access | Grok3.5 limited availability for select users | X Premium+ & SuperGrok ($30/month) |
| Heavy/Advanced | Grok3.5 advanced features not available | SuperGrok Heavy ($300/month) for multi-agent reasoning |
| API | Grok3.5 limited API access with usage restrictions | Pay-as-you-go ($3 input / $15 output per million tokens); available on hyperscaler partners |
Why Choose Grok3.5?
Grok3.5 Cost-Effectiveness
- Grok3.5 offers excellent value for money compared to premium models
- Grok3.5's lower computational requirements mean faster response times
- Grok3.5 provides reliable performance for everyday AI tasks
- Grok3.5's efficiency makes it ideal for budget-conscious users
Grok3.5 Reliability
- Grok3.5's proven track record with consistent performance
- Grok3.5 offers stable API access with minimal downtime
- Grok3.5's mature architecture ensures predictable behavior
- Grok3.5 provides excellent support for legacy applications
Conclusion
Grok 4's substantial upgrades in scale, context capacity, autonomous tool use, and parallel reasoning make it a transformative model for high-stakes research, coding, and creative applications—surpassing Grok3.5's incremental improvements in reasoning and multimodality. While Grok3.5 remains a solid choice for users seeking reliable, cost-effective AI assistance, Grok3.5's limitations in context window size and advanced features become apparent when compared to Grok4. However, Grok3.5 continues to serve as an excellent entry point for users new to advanced AI models, offering Grok3.5's proven capabilities at a more accessible price point. The choice between Grok3.5 and Grok4 ultimately depends on your specific needs, budget, and the complexity of tasks you plan to tackle.