BANJO IDENTIFICATION FOR NON-EXPERTS
This is a quick and dirty means of general banjo identification ..... as you can see, there are many variations on the theme. The pictures are not to scale.
The earliest type is the Gourd Banjo, made, as you might expect, from a gourd cut in half, a fretless neck added, and a skin head.
The Minstrel Banjo is fretless, with a very simple, very large ring and neck.
As a general rule-of-thumb, any banjo with a thin, metal clad ring / body was probably made before 1900 and should use gut or nylon strings only.
The Standard banjo has five strings, and approximately 22 frets on the neck (give or take a couple). It was developed before the 4-string models. The Longneck banjo adds three extra frets between the fifth string and the peghead. The Banjaurine is usually five frets shorter than the standard banjo.
There are other variations on the theme: the Fretless banjo has no frets. The A-Scale banjo is approximately two frets shorter than the Standard banjo, and is tuned in "A" rather than the standard "G."
The Piccolo banjo can be either seven frets shorter than the Standard, and tuned in "D," or it can be about the same neck length as a Banjo-Ukelele and tuned one octave higher than Standard, while the Mandoline-banjo has a Banjaurine neck on a mandolin body.
All of these have five strings, and the fifth peg is usually attached about five frets down from the peghead.
The Tango banjo has only 15 frets, and is four stringed. The Tenor banjo has between 17 and 19 frets, and is four stringed, while the Plectrum banjo has a similar number of frets as the five-string, but has only four strings.
The Banjo-Ukelele has a ukelele neck (very short with four strings) on a (usually) very small banjo body.