Basically everything I say about bonnet cleaning applies to dry methods. Some of them are higher productivity than bonneting tho.
You will hear brand names like Host, Chem Dry, Whittaker and a bunch of others instead of “dry” tho – so when you hear a brand name it probably really means some form of dry carpet cleaning.
Extraction – either self contained or via a truck mounted rig will usually be referred to as extraction, or, improperly as shampooing.
The one difference is that while bonneting, properly done, uses almost no water and leaves the carpet dry in a couple of hours, dry products use no water at all and the carpet is dry immediately.
You first vacuum the carpet to pull as much dirt as possible out (also true with bonneting) spread a powder that “encapsulates” dirt – similar chemistry to the emulsification of a solvent or detergent carpet cleaner – and then agitate it with a brush system to get the soil to adhere to the “capsule”.
You then vacuum up the chemical – dirt attached.
My bias is that this has a higher probability of leaving more chemical in the carpet, thus having a higher probability of resoiling than bonneting – but properly done with no overuse of chemical both should give about the same result.