Nearly fainted today when I saw that posted on FB. Sigh. The supporting evidence being: http://www.amazon.com/Yamaha-Guitar-Ukulele-Guitalele-GL1/dp/B004N6RBWW
As for the differences between four string ukuleles and six string guitars, one of the biggest differences in music is the difference between minor and major keys or scales. On both the guitar and the ukulele fretboard the physical implementation of this huge musical difference is one fret space on the third note of any scale, a distance of less than 3/4 of an inch in most cases. This physically small distance makes a big difference in the sound of the music you play. The same analogy applies to the guitar and the ukulele.