Factory habitats are spindle shaped stations.
The habitat ring is a Stanford Torus connected to a spindle containing the industrial components. They are more mobile than other habitat types.

Color Coding:
Red = Docking facilities and shipyards
Blue = Liquid and Gaseous Ressource Tanks
Violett = Industrial Modules
Yellow = Decoupler and Logistics Depot
Green = Habitat Section

They differ vastly in size, depending upon their specific tasks, same as their individual configuration. some keep the spindle stationary, others have the spindle rotate.
Their main difference compared to most other habitats is that they are free floating, and usually lack a dedicated static outer, all-encompassing, shell.

As an example there are scraps from the space station Odin:

On the space station Odin, a 5 month trip away from Asgard, the Terra Observation Group, TOG, is stationed.
Odin maintains several large grids of both optical and radio telescopes, and TOG sorts and processes the data the two 100 million km² grids aimed toward the solar system and earth specifically produce.
These two array telescopes, grids of thousands of container-sized space telescopes, are called Hugin ( Thought; the radio telescope array ) and Munin ( Memory, the optical telescope array ).

Odin is at the nadir of the Tau Ceti system, i.e. it is below the southpole of the sun Tau Ceti. Vast solar sails provide electrical power as well as doing the main work of keeping the station in place.
In the large ring-shaped habitat section of the station there are two cities, one costal, one in a a rich farm and meadow country, two villages, one in hilly wine country, the other in a forested mountain area, and all are spearated from each other by intervening landscapes, one even being a shallow saltwater "ocean" of 2km width

6km outer diameter, 4km wide habitat ring, 16km spindle length, spindle 1km diameter.
Habitat 18,2km "length", 3.2 km wide, 8 sections a 2,2km length:

Coastal City "New York" Industry & Administration, food processing,
Saltwater Ocean "Atlantic" fishing and crustaceans,
Hilly wine country village "Patras" Wine and nuts, tourism
Farming country "Orjol" Wheat & Rye and apples.
Farmland City "Almaty" telescope operations and management, food processing,
Mountain area "Kunlun Range", specialty plants and hiking tourism,
Mountain Forest village "Takayama" small cattle operations, handcraft arts, tourism.
Farming country "Mendoza", maize and beans and potatoes but also fruits.

The differences between inner measurements and outer shell come from the large volume used by storage, shielding and balancing areas embracing the habitation area.

Each 2.2km element is isolated by pseudo mountain ranges from the next, as a precaution against catastrophic decompression effects. These pseudo mountain ranges contain several large airlocks as well as smaller ones, left open for wildlife to pass through during normal operation.

With the exception of the oceanic module, each 2.2km element contains underground facilities that make each module a fully functional spacecraft with a 30 years operation time, of which ten years should be enough to get an element to one of the inner system emergency centers under its own power.

The Disco "Odins Eye" is located in the "New York" element. Its special feature is a huge, meter thick window looking out into space when its meteorite shields are opened.