Short answer: At Cozey, we make Cassini for curved layouts, a low seat and a compact footprint, and Atmosphere for deeper seating with chaise, storage and sleeper options. Both have medium-firm seats and removable, machine-washable covers. Choose Cassini for shape and size, and Atmosphere for function.
Both sofas look modern and both feel supportive, so the choice is rarely about comfort alone. It comes down to the shape of your room and whether the sofa needs to store things or host a guest. This page helps you make that one decision and links the full guides for the detail.
On This Page
- What is the main difference between Cassini and Atmosphere?
- How do the sizes compare?
- Which feels softer, firmer, lower or deeper?
- Which has more layout options?
- Which suits a small living room?
- Which is better for guests, storage or an open-plan room?
- How do the covers and fabrics compare?
- What goes on the wall or beside each sofa?
- What if neither sofa fits?
- Our recommendation
- Explore our sofas
What is the main difference between Cassini and Atmosphere?
The main difference is that Cassini curves and Atmosphere does more. Cassini has rounded arms and backrests and a 45-degree wedge module that bends a sectional into a gentle curve or a rounded corner. Atmosphere has a square or a round style, and it adds a chaise, an ottoman, a long ottoman, a storage version and a sleeper version.
They share a lot. Both are modular, both use layered foam seating that keeps its shape without routine fluffing, and both have removable covers that you can machine wash. Our guides to Cassini and Atmosphere cover each collection on its own, and which Cozey sofa is right for you compares all of them.
How do the sizes compare?
Atmosphere is the bigger sofa in every direction. The figures below come from the module sizes we publish, and depths are rounded to the nearest half inch.
How do the sizes compare?
| Cassini | Atmosphere | |
|---|---|---|
| Seat depth | 26.5 inches | 27.5 inches square back; 29.5 inches round back |
| Seat height | 17 inches | 17.5 inches Regular; 18.1 inches Storage; 17.3 inches Sleeper |
| Backrest height | 27.8 inches | 29.1 inches square back; 30.9 inches round back |
| Overall depth of an armless seat and back | 36.0 inches | 40.5 inches square back; 38.5 inches round back |
| Armless seat width | 26.4 inches | 29.5 inches |
| Armless two-seater | 52.8 inches | 59.1 inches |
| Armless three-seater | 79.1 inches | 88.6 inches |
In a comparable three-seat layout, our Cassini product page puts Cassini about 12 inches narrower and 4.5 inches shallower than Atmosphere. Atmosphere seat heights are 17.5 inches Regular, 18.1 inches Storage and 17.3 inches Sleeper, against 17 inches for Cassini, so the gap is small, between 0.3 and 1.1 inches, and both sit low. Atmosphere is deeper in the seat, about 1 inch with the square back and 3 inches with the round back. Our seat depth and height guide compares every collection side by side.
Which feels softer, firmer, lower or deeper?
Both are medium-firm, so neither is a cloud-like sofa. Each has layered high-density foam that gives a little at first and then supports. Our sofa comfort guide places Cassini slightly firmer than Atmosphere, with a more structured back.
The seat shapes differ more than the firmness. The Cassini seat is gently inclined toward the back, which gives a relaxed, cradled position, and it is lower and shallower, so it suits upright sitting and reading. Atmosphere has a deeper seat that suits sitting cross-legged or lounging, and its round style adds lumbar pillows and slightly taller backs for more support. If you want a very soft, sink-in sofa instead, look at our Ciello and Gaia comparison or our Atmosphere vs Ciello comparison.
Which has more layout options?
It depends on what you mean by layout. Cassini has more shapes, and Atmosphere has more functions.
- Cassini shapes: straight seats, conventional corners and 45-degree wedges. One wedge between seats gives a gentle bend, and two wedges side by side turn a full 90 degrees with a rounder corner than a square module. Layouts run from a single seat to four- and six-seat U shapes.
- Atmosphere functions: left, right or double chaise on the Regular and Storage versions, an ottoman, and a long ottoman that works with the square back only. Layouts run from one seat to a seven-seat U.
- What neither does: Cassini has no chaise, no storage version and no sleeper. Atmosphere has no wedge, so its layouts turn at right angles.
Atmosphere also has limits to plan around. Its Regular, Storage and Sleeper modules differ in seat height (17.5 inches Regular, 18.1 inches Storage and 17.3 inches Sleeper) and are not compatible with one another, so choose the version before you plan the layout. Cozey Studio is our online configurator where you build a sofa from our collections one module at a time, with only the modules that can attach next on offer. Build a Cassini and an Atmosphere with the same number of seats and compare their overall dimensions, which appear on screen, against your wall.
Which suits a small living room?
Cassini suits a small room better, and it is the one we point to first for tight spaces. Our Cassini product page notes that an armless two-seater is about 53 inches wide and that a compact L-shaped layout fits within roughly 62.5 inches on each side. The shallower body, at 36.0 inches overall, also leaves more floor in front of the sofa.
Atmosphere can still work in a smaller room if you choose carefully. Its round arms are about 2 inches slimmer per side than the square arms, and a two-seater with two arms is 77.2 inches wide in the round style and 81.1 inches in the square style. Measure the wall and the walkway before you decide, and use our guide to sofas under 80 inches and our guide to measuring stairs, elevators and doorways for the route in.
Which is better for guests, storage or an open-plan room?
Atmosphere is the better choice for guests and for storage, and Cassini is the better choice for shaping an open-plan room. The Atmosphere Sleeper version opens to a surface of 88.6 x 59.1 inches, and the Storage version holds 79.4 liters in each seat, corner and ottoman. Our Atmosphere guide and Neptune vs. Orian vs. Atmosphere Sleeper cover both in detail.
Cassini has neither, but its wedges let a sectional soften the line between a living area and a dining or entry area. If you want a chair beside it, our Cassini lounge chair has the same curved design and pairs with the sofa.
How do the covers and fabrics compare?
Both sofas have removable, machine-washable covers, and both let you change the fabric later with replacement covers. Cassini comes in two fabrics and 12 colors, while Atmosphere offers more fabrics and a wider palette. Abrasion resistance is measured in Martindale double rubs, and a higher number means more resistance.
How do the covers and fabrics compare?
| Fabric | Martindale | Cassini | Atmosphere |
|---|---|---|---|
| Performance Chenille | 48,000 | Yes: Sage, Frost, Espresso, Bordeaux | Yes, with more colors, including Harbor Blue, Cobblestone and Carbon |
| Aquaforte Velvet | More than 200,000 | Yes: eight colors | Yes: eight colors |
| Performance Textured Weave and Textured Weave | 54,000 | No | Yes |
| Bouclé (Cloud) | 15,000 | No | Yes, square back only |
| Corduroy | 15,000 | No | Storage and Sleeper versions only |
In our own assessment, Aquaforte Velvet is excellent for pets and Performance Chenille is good. Our Aquaforte Velvet colors guide shows all eight velvet colors, and our sofa color guide helps you narrow them down. Judge a shade in your own light with free swatches. Wash covers cold on a gentle cycle and air dry them. Our Cloud bouclé is machine washable, but we advise spot cleaning it to maintain its look.
What goes on the wall or beside each sofa?
Plan the wall at the same time as the sofa. Our Themis modular wall system has shelf and cabinet units that are 32.0 inches wide and 11.0 inches deep, and each unit holds 50 lb. Our Altitude wall shelves and cabinet are shallower at 9.5 inches deep, which keeps a small wall light above a compact Cassini.
A deeper Atmosphere sectional can handle the greater depth of Themis, and its chaise or long ottoman needs clear floor beside it. Check how far the sofa and the wall units project before you order.
What if neither sofa fits?
Our six collections cover different needs, so here is each one in a line.
- Ciello: very soft, cloud-like seating with loose cushions.
- Gaia: the same seat comfort as Ciello with large French seams and a more relaxed upholstered look.
- Cassini: a curved, low, compact sofa with 45-degree wedge modules.
- Atmosphere: medium-firm, deep seating with chaise, storage and sleeper options.
- Neptune: a firm sofa bed with the tallest back of our sofa beds.
- Orian: a compact sofa bed that opens to a queen-size bed.
To plan the whole order, read buying a sectional online.
Our recommendation
At Cozey, we suggest choosing by the shape of your room first and by function second. Pick by how you use the room:
- A small living room or condo: Cassini, in a two-arm loveseat or a compact L.
- A curved or open-plan layout: Cassini, with one or two wedges.
- Overnight guests: Atmosphere in the Sleeper version.
- Hidden storage in more than one seat: Atmosphere in the Storage version.
- A chaise or a long ottoman: Atmosphere.
- A deep seat for lounging: Atmosphere, with the round back for the deepest sit.
- A low, upright sit: Cassini.
If you are still unsure, preview a layout in Cozey Studio, order free swatches, or book a free design consultation and our team will look at your room with you.
Explore our sofas
More Cozey comparisons: Cassini vs Gaia, Atmosphere vs Gaia, Cassini vs Ciello, Ciello vs Gaia, Atmosphere vs Ciello.
Product specifications can change. Check the current dimensions on the product page before ordering.