1. Yamato has bright hair while Kaido had dark hair, showing their contrast. Dont know if the horns are apart of the mask but the shading is still the opposite of Kaido's horns.
2. Yamato is wearing Hannya mask which flows well with the theatre/play theme of the Beast Pirates(All Star, Headliner etc)
3. The hannya mask is that of a jealous evil spirit and Kaido has a belt that wards off evil spirits, again showing their contrast
4. Hannya masks are regularly depicted with a snake or dragon in its mouth, again alluding to Kaido.
5. There was a japanese prince named Yamato and his father, the Emperor, was believed to have had gigantism and 80 children(BM and her 85 kids?). Also, that emperor kinda looks like Kaido.
6. The name Yamato means Great Harmony or Spirit and is associated with the spirit of the Japanese people, and was popular among Samurai.