GPT-5.5 38.7/100Rank 36/502 of 3 levels

STEALTHMARK · HEAD TO HEAD
All comparisons ↗GPT-6.1 Terra leads GPT-5.5 by 23.9 points on StealthMark, 60.4 to 36.5. It leads on all 9 benchmarks. GPT-6.1 Terra scores higher on Newton's Mirror, with its largest category advantage in reflections.
See the difference ↘On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.
BENCHMARK BY BENCHMARK
DATASHEET
GPT-6.1 Terra scores higher on StealthMark and is 6× cheaper per output token. Both take about 1.05M tokens of context.
Full datasheets, every price and sourceGPT-5.5 ↗GPT-6.1 Terra ↗
Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.


Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.


Physics, perspective and recursive reflections, tested together. Explore the test ↗


GPT-5.5
The paint ordering and separate black bead support part of the physical state, but adhesion and rotational transport remain only partly established. The sweeping cyan arc and long crimson lobes do not clearly communicate the limited time since their respective impacts. The main sphere is too large and too low, and the black bead is below its required projected position. Displaced isolated sphere images, a flattened floor echo and missing recursive, nested and emitter reflections provide little coherent optical structure. The colored paint is excessively bulky for the specified quantities.
GPT-6.1 Terra
The sphere, airborne black and first reflected silhouettes preserve important geometry within the portrait frame. Paint deformation, contact order and forward transport are supported, with a small crimson endpoint overshoot. Major optical omissions dominate: short finite reflection sequences and smooth bands replace extensive, spatially ordered mirror imagery. Dark gloss and crisp upper emitter shapes provide partial material credit.
| Category | GPT-5.5 | GPT-6.1 Terra |
|---|---|---|
| State at 600 ms | 15.0/25 | 23.0/25 |
| Camera and placement | 6.0/15 | 11.0/15 |
| Reflections | 5.0/120 | 33.0/120 |
| Materials and scale | 6.0/10 | 7.5/10 |
| Floor-damage reward | 0.0/10 | 0.0/10 |
A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.
Visual construction and creative interpretation.


GPT-5.5
Six pale, scaled lobes form a balanced radial arrangement, but they remain separate capsules rather than an interlocking serpent knot. There are no crossings, alternating overlaps, or crisp inner bends; the central hexagon is an isolated outline. Small outward-facing heads sit within the lobes without integrated necks. Soft shading and tidy contours provide some finish, while repetitive oval scales and cartoon faces limit organic credibility.
GPT-6.1 Terra
A balanced serpent emblem with six attached outward heads, delicate scales and softly rounded bodies. Its compact silhouette reads clearly, but central routing does not establish every alternating crossing or crisp inward corner. Repetitive texture, limited facial anatomy and weak contact shadows constrain its organic character.
| Category | GPT-5.5 | GPT-6.1 Terra |
|---|---|---|
| Task & likeness | 3.0/10 | 7.5/10 |
| Anatomy & construction | 3.0/10 | 6.5/10 |
| Space & placement | 5.0/10 | 6.5/10 |
| Light & reflections | 5.0/10 | 6.0/10 |
| Purposeful detail | 4.5/10 | 6.5/10 |
| Artistry & character | 4.0/10 | 6.5/10 |
| Materials & effects | 4.5/10 | 6.0/10 |
| Visual integrity | 7.0/10 | 6.0/10 |
A pale serpent woven into an interlocking knot tests connected anatomy, repeated structure and readable overlaps. Organic surface detail must work with the overall geometry.
Precise visual recall and portrait reconstruction.


GPT-5.5
The veil, restrained smile, crossed hands and muted landscape establish Mona Lisa references. The oversized frontal face and schematic features weaken likeness and expression, while fingerless tapered hand shapes leave anatomy unresolved. Clean contours and balanced framing provide coherence, but sparse garment detail, broad landscape bands and shallow shading limit the portrait's sophistication.
GPT-6.1 Terra
A recognizable interpretation with developed facial shading, shaped sleeve folds and purposeful small features. These strengths support modest upward calibration, while the frontal torso, elongated proportions, schematic finger joints and unresolved seated support keep replication and construction uneven.
| Category | GPT-5.5 | GPT-6.1 Terra |
|---|---|---|
| Task & likeness | 1.5/10 | 5.5/10 |
| Anatomy & construction | 1.5/10 | 6.5/10 |
| Space & placement | 1.5/10 | 4.5/10 |
| Light & reflections | 2.0/10 | 6.5/10 |
| Purposeful detail | 2.5/10 | 6.0/10 |
| Artistry & character | 1.5/10 | 6.0/10 |
| Materials & effects | 2.0/10 | 6.0/10 |
| Visual integrity | 1.5/10 | 6.5/10 |
An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.
Creativity, perspective and visual beauty.


GPT-5.5
The sunset, palms, birds, playful animals and ball clearly establish the requested beach scene. Warm sky gradients and clean silhouettes make it appealing. Animal construction is underdeveloped: torso and limb connections are unclear, especially in the round-eared foreground figure. The dolphin lacks a convincing splash, and broad reflection bands suggest sunset light without resolving its behavior on water.
GPT-6.1 Terra
A coherent sunset illustration with clear prompt fulfillment, controlled framing and varied, purposeful small details. Simplified joints, frontal staging, flattened animal forms and weakly directional shadows limit its anatomical, spatial and physical sophistication.
| Category | GPT-5.5 | GPT-6.1 Terra |
|---|---|---|
| Task & likeness | 7.0/10 | 8.5/10 |
| Anatomy & construction | 2.5/10 | 7.5/10 |
| Space & placement | 3.0/10 | 6.5/10 |
| Light & reflections | 3.0/10 | 5.5/10 |
| Purposeful detail | 3.0/10 | 7.5/10 |
| Artistry & character | 3.0/10 | 7.0/10 |
| Materials & effects | 3.0/10 | 6.5/10 |
| Visual integrity | 3.5/10 | 7.5/10 |
A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.
Physical reasoning, light and visual reconstruction.


GPT-5.5
This benchmark has not been assessed yet.
GPT-6.1 Terra
This benchmark has not been assessed yet.
A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.
Scene composition and interacting subjects.


GPT-5.5
The raccoon's masked face, bright hull and sweeping wake make the scene readable and lively. The dog is much less resolved: its head is ambiguous, overlapping brown forms obscure its anatomy, and its paws do not visibly grip the controls. Smooth shapes and cheerful colors provide appeal, but weak steering construction and limited depth keep the drawing uneven.
GPT-6.1 Terra
A coherent cartoon with expressive animals, readable steering and a clear wake. Fine facial and hull details reward inspection. The main limits are the boatlike craft, simplified joints, weakly braced frontal raccoon and minimal directional lighting or material depth.
| Category | GPT-5.5 | GPT-6.1 Terra |
|---|---|---|
| Task & likeness | 3.5/10 | 6.5/10 |
| Anatomy & construction | 3.0/10 | 5.5/10 |
| Space & placement | 4.5/10 | 6.0/10 |
| Light & reflections | 5.0/10 | 5.0/10 |
| Purposeful detail | 3.5/10 | 7.0/10 |
| Artistry & character | 3.0/10 | 6.0/10 |
| Materials & effects | 5.0/10 | 6.0/10 |
| Visual integrity | 3.0/10 | 7.0/10 |
A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.
Subject construction and spatial relationships.


GPT-5.5
The oversized bill, bright bicycle and sunset create an appealing, recognizable cartoon. Riding mechanics are less convincing: the wing has no clear steering contact, leg attachments are uneven, and feet do not visibly engage pedals. A dark notch complicates the rear neck junction. Clean contours and orderly spokes provide polish, while simplified anatomy and lighting limit depth.
GPT-6.1 Terra
A coherent pelican cyclist with expressive proportions, purposeful feather detail and developed bicycle machinery. Continuous body contours, aligned wheels and readable pedal contacts support the scene. Simplified articulation, shallow modelling and an unresolved steering connection limit construction and placement.
| Category | GPT-5.5 | GPT-6.1 Terra |
|---|---|---|
| Task & likeness | 7.5/10 | 7.0/10 |
| Anatomy & construction | 4.5/10 | 7.0/10 |
| Space & placement | 6.5/10 | 6.0/10 |
| Light & reflections | 6.5/10 | 5.5/10 |
| Purposeful detail | 5.5/10 | 7.0/10 |
| Artistry & character | 5.0/10 | 6.5/10 |
| Materials & effects | 6.0/10 | 5.5/10 |
| Visual integrity | 7.5/10 | 6.0/10 |
A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.