Ukuleles come in three different sizes: soprano, concert, and tenor. The soprano was the first size, and all ukuleles were originally sopranos. Approximately 20 years later, the concert size was introduced. Then, another 20 years after that, the tenor size was introduced.
The soprano, concert, and tenor sizes are all tuned the same, but they differ in terms of the spacing of the frets and the tone they produce. Sopranos have a punchy sound, while tenors have a rounder sound. The choice of size often comes down to personal preference and comfort.