Firearms associated with the name Česká zbrojovka ("Czech Armory" in Czech), often rendered simply as "CZ" have been produced by various factories that have been mutually independent in their management and ownership.
The factories include:
Firearms made in many different factories in Czechoslovakia and later the Czech Republic have been sold under the name CZ, Brno or Vz.
CZ (or ČZ) is an abbreviation of Česká zbrojovka. Vz (or Vz., vz, vz.) is an abbreviation of vzor ("model"). In most cases, only weapons adopted by the Czechoslovak or Czech military have sign "vz." in the name (e.g. the CZ 75 pistol was not adopted by the military, so there is no "vz. 75" pistol), although there are some exceptions from this rule. Sa (or Sa.) is an abbreviation of samopal ("submachine gun"). The Czech army used the term "samopal" for Sa vz. 58 though it is an assault rifle, so this may be as an analogy to Russian term automat.
Note that military weapons were after World War II designed by several independent development centers (e.g. ZVS-VVÚ Brno, VTÚVM Slavičín etc.) and then assigned to a production factory.
Czech Weapons (ČZW) is a subsidiary group of Česká Zbrojovka who develops and evaluates firearm platforms.