Every manufacturer was free to make up its own scheme, and often a given manufacturer would change its numbering scheme over the years. Model numbers are often printed on a paper label glued to the back, inside, or bottom of the radio cabinet. On my Electrohome console , for example, the label is stapled to the cabinet underside. The label usually contains other information, such as a serial number, tube diagram, or even a complete schematic diagram. The model number may also be printed somewhere on the cabinet itself.
Many radios have a serial number in addition to a model number.
If you see a Philco radio whose model number starts with two digits and a dash, the the first two digits indicate the year of manufacture. For example, my Philco 46-420 was made in 1946. The name may be handy if a collector guide happens to list your set by name instead of by model number. And, if you're communicating with other collectors, they may remember a name more readily than a number. Let's say that you've got the manufacturer and model number, and perhaps a name as well.