TNG s4e23 “The Host” with shots from DS9 s5e7 “Let He Who Is Without Sin…”
Although the writers of DS9 were obviously aware of the physical differences between Odan and the Trill in DS9, no canon explanation has ever been offered. In an attempt to explain the variations, Terry Farrell once suggested that the spotted members of the species were from the north of Trill whereas Odan was from the planet’s south.
Good luck explaining the difference between the Romulans and Remans.
Vitamin D.