My UBass and my baritone ukulele arent from the same maker, and I cant guarantee for the last 1/1000 of an inch, but the string lengths appear being very similar.
However I see no way to mount Pahoehoe strings on my baritone ukulele. Neither tuners nor bridge would fit.
Without dissecting neither of the instruments I would say that the UBass has a bigger headstock, bigger tuners, a fatter and wider neck, a compensated bridge high enough allowing for larger string amplitude, and a dedicated mounting system for the fat strings. I might assume differences in thickness of the soundboards and in the strength of the bracing.
And despite the congruency in string names: my retuned baritone ukulele plays an octave above the UBass.
Klaus
Thanks for the response and explanation.