Diffuse and volume discharges are currently used widely in various fields. This work compares the properties of diffuse and volume discharges

as well as considers the conditions for their formation at high pressures. The main attention is paid to a diffuse discharge (DD). It has been shown that the ignition of a diffuse discharges is preceded by the development of a wide streamers. In the case of a volume discharge

the streamers usually have a small diameter and an ionisation waves emerging from it passes into the spark leader with subsequent discharge constriction. There are images and emission spectra of diffuse discharges in air and nitrogen in the paper. It has been confirmed that a diffuse discharges initiated by a nanosecond voltage pulse in a point-to-plane gaps has a uniform effect on the surface of a flat electrode. It was found that thin tracks of luminous particles are observed against the background of the DD plasma glow. They are associated with sputtering of the pointed electrode material due to the large field enhancement on the macro- and microinhomogeneities.