The two dominant AI image generation platforms for architectural visualization concept work are Nano Banana 2 (NB2) and Stable Diffusion XL (SDXL). Both can produce stunning architectural imagery from text prompts, but they approach the task with fundamentally different strengths. NB2 excels at photorealistic rendering with accurate spatial relationships. SDXL excels at artistic interpretation with superior material diversity and stylistic control. Choosing the right tool for each phase of your project workflow can save hours of iteration and produce better results than defaulting to either one exclusively.
This comparison is not theoretical — we generated identical prompts through both platforms across eight architectural scene types, evaluated the outputs against five ArchViz-specific criteria, and documented where each tool genuinely outperforms the other.
Testing Methodology
We used 24 prompts (3 per scene type) written in the constraint-first structure documented in our hallucination control article. Each prompt was run through NB2 (default settings, 4 generations per prompt) and SDXL 1.0 with the RealVisXL fine-tune (same seed range, 30 sampling steps, CFG 7.0). Best-of-4 selections were evaluated by three senior ArchViz artists using a blind comparison format.
Evaluation Criteria (scored 1–10)
- Spatial Accuracy: Room proportions, ceiling heights, window positions match prompt description
- Material Realism: Surface textures look physically correct (not painted or stylized)
- Lighting Quality: Light behavior is physically plausible (shadow direction, bounce light, exposure)
- Prompt Fidelity: Output matches what was requested, not what the model "prefers"
- Production Usability: Output can be used as a direct reference for 3ds Max scene building
Benchmark Results
Scene Type Comparison (averaged across 3 prompts each)Scene Type | NB2 Spatial | SDXL Spatial | NB2 Material | SDXL Material
------------------------|-------------|-------------|--------------|---------------
Modern Interior | 8.5 | 6.5 | 8.0 | 7.5
Traditional Interior | 7.5 | 7.0 | 7.0 | 8.5
Exterior Residential | 8.0 | 6.0 | 7.5 | 7.0
Exterior Commercial | 7.0 | 5.5 | 7.0 | 6.5
Landscape / Garden | 6.5 | 7.0 | 7.0 | 8.0
Interior Detail (close) | 7.0 | 6.5 | 8.5 | 8.0
Aerial / Masterplan | 8.5 | 4.5 | 6.0 | 5.5
Night Exterior | 7.5 | 7.5 | 7.5 | 8.5Overall Scores (all scene types averaged)Criterion | Nano Banana 2 | Stable Diffusion XL
--------------------|---------------|--------------------
Spatial Accuracy | 7.6 | 6.3
Material Realism | 7.3 | 7.4
Lighting Quality | 8.0 | 7.2
Prompt Fidelity | 7.8 | 6.0
Production Usability| 8.2 | 6.5
--------------------|---------------|--------------------
OVERALL AVERAGE | 7.8 | 6.7Where Nano Banana 2 Wins
Spatial Accuracy (+1.3 average advantage)
NB2 consistently produces rooms with correct proportions, plausible ceiling heights, and window placements that match the prompt description. The advantage is most dramatic in aerial/masterplan views (+4.0 points) where NB2 maintains coherent building footprints and urban layouts while SDXL produces spatially incoherent arrangements. For production reference images where architectural accuracy matters, NB2 is the clear choice.
Prompt Fidelity (+1.8 average advantage)
NB2 follows prompt instructions more literally. When you specify "single window on the north wall," NB2 produces a single window. SDXL frequently interprets this as "windows on the north wall" and adds multiple openings. This literal adherence is critical for ArchViz where the prompt describes a specific architectural design, not a creative interpretation of one.
Production Usability (+1.7 average advantage)
NB2 outputs serve as better direct references for 3ds Max scene construction. The consistent spatial relationships mean you can estimate room dimensions, furniture scale, and camera angles from the generated image with reasonable accuracy. SDXL outputs require more interpretation and adjustment during the 3D modeling phase.
Where Stable Diffusion XL Wins
Material Diversity and Texture Quality
SDXL with the RealVisXL fine-tune produces superior organic textures — aged wood, weathered concrete, natural stone with visible geological stratification, patinated metal. NB2 materials tend toward a "showroom clean" aesthetic that looks excellent for new-build visualization but lacks the lived-in material character needed for renovation projects, heritage architecture, or rustic design concepts.
Artistic Mood and Atmosphere
For night exteriors, moody interiors, and atmospheric landscape concepts, SDXL produces more emotionally compelling images. The model's artistic training data gives it stronger understanding of dramatic lighting, color temperature contrast, and compositional mood — qualities that are valuable in early concept presentations where selling the emotional feel of a space matters more than dimensional accuracy.
ControlNet Ecosystem
SDXL's open-source nature provides access to the full ControlNet suite — depth maps, edge maps, segmentation masks, normal maps — giving you granular control over the generation process. NB2's ControlNet equivalent is improving but currently less flexible. For workflows where you provide a 3ds Max depth render as input (see our hallucination article), SDXL's ControlNet depth model produces more reliable spatial adherence than NB2's equivalent.
The Hybrid Recommendation
The optimal workflow uses both tools at different project phases:
Recommended Tool by Project PhasePhase | Recommended | Reason
-------------------------------|-------------|-------
Early concept exploration | SDXL | Artistic variety, mood exploration
Client mood board presentation | SDXL | Emotional impact, material diversity
Spatial layout reference | NB2 | Accurate proportions for modeling
Material palette extraction | SDXL | Richer texture detail for sampling
Camera angle reference | NB2 | Reliable perspective geometry
Final concept presentation | NB2 | Professional, production-ready output
ControlNet-guided refinement | SDXL | Superior ControlNet ecosystem
Heritage / renovation concepts | SDXL | Better aged/weathered materials
New-build modern concepts | NB2 | Clean, precise architectural stylePrompt Syntax Differences
The same concept requires different prompt structures to get optimal results from each platform:
Prompt ComparisonCONCEPT: Modern penthouse living room with floor-to-ceiling windows
NB2 PROMPT (constraint-first, literal):
"Photorealistic interior photograph of a modern penthouse living room,
8m × 6m floor area, 3.2m ceiling height, floor-to-ceiling windows on
south wall only, polished concrete floor, white plaster walls, minimal
furniture — single L-shaped sectional sofa in dark gray fabric, walnut
coffee table, no additional furniture, daylight from south windows,
architectural photography, Canon EOS R5, 24mm lens"
SDXL PROMPT (weighted tokens, artistic):
"(masterpiece:1.2), (best quality:1.1), photorealistic interior,
modern penthouse living room, (floor to ceiling windows:1.3) on one
wall, polished concrete floor, white walls, (minimal furniture:1.2),
dark gray sectional sofa, walnut coffee table, natural daylight,
(architectural photography:1.3), wide angle lens, 8k uhd"
SDXL NEGATIVE:
"extra windows, cluttered, busy, cartoon, illustration, painting,
low quality, blurry, distorted architecture"NB2 responds better to specific dimensions and literal descriptions. SDXL responds better to quality boosters and weighted emphasis tokens. Writing prompts optimized for each platform's syntax produces noticeably better results than using the same prompt verbatim in both.
Performance and Cost Comparison
Operational ComparisonFactor | Nano Banana 2 | SDXL (local RTX 4090)
--------------------|---------------------|----------------------
Generation time | 8-15 sec/image | 12-25 sec/image
Cost per image | ~$0.02 (API) | ~$0.003 (electricity)
Max resolution | 2048×2048 | 1024×1024 (native)
Batch capability | API queue | ComfyUI batch
ControlNet support | Limited | Full ecosystem
Fine-tuning | Not available | LoRA, DreamBooth
Privacy | Cloud (data uploaded)| Local (fully private)
Setup complexity | Minimal (API/web) | Moderate (Python env)For studios handling confidential architectural projects (unreleased developments, competition entries), SDXL's local execution is a significant advantage — no project imagery is uploaded to external servers. NB2's cloud-based processing is faster and simpler but requires trusting the provider with potentially sensitive design data.
Key Takeaways
Neither tool is universally superior for ArchViz concept work. NB2 produces more architecturally accurate, production-ready output — use it when spatial fidelity and prompt adherence matter. SDXL produces more artistically compelling, materially rich output — use it for mood exploration, material palette development, and projects requiring aged or atmospheric aesthetics. The highest-quality concept workflows use both tools strategically, leveraging each platform's strengths at the appropriate project phase rather than defaulting to one for everything.
Using a different AI platform for ArchViz concepts? Share your experience — we include reader-tested tools in our comparison updates.