Fires burning with lack of oxygen produce a significantly wider palette of compounds, many of them toxic.

Sulfur content yields sulfur dioxide, or in case of incomplete combustion, hydrogen sulfide.[7] Carbon and hydrogen are almost completely oxidized to carbon dioxide and water.

High temperature also leads to production of nitrogen oxides.

the particles are mostly composed of ash, or with large temperature differences, of condensed aerosol of water.

Fires with high availability of oxygen burn at a high temperature and with a small amount of smoke produced; 

The composition of smoke depends on the nature of the burning fuel and the conditions of combustion. 

Smoke is an aerosol (or mist) of solid particles and liquid droplets that are close to the ideal range of sizes for Mie scattering of visible light.

The smoke kills by a combination of thermal damage, poisoning and pulmonary irritation caused by carbon monoxide, hydrogen cyanide and other combustion products.

Smoke inhalation is the primary cause of death in victims of indoor fires. 

It can also be a flavoring agent and preservative.