Server Rack Cabinets are 19-inch wide, industry standard racks. They are generally used to install servers, monitors, UPSes, and the like. Server rack cabinets are typically 24” in overall width, and approximately 36” in depth, but other options do exist. These cabinets often have perforated front and rear doors for ventilation, to maintain a suitable environment for the heat-generating equipment inside.
Network Cabinets are mainly used to store routers, switches, patch panels and other types of networking equipment and accessories. These cabinets are usually shallower than server rack cabinets, and they are often times less than 31” in depth. Networking cabinets are more likely to have a glass/Plexiglas front door rather than a perforated one, because thermal requirements are not a typical issue.
Hopefully these simple definitions will help you navigate to the product that best fits your environment.