Board Thread:Versus Debates/@comment-28381997-20160509220110/@comment-4912646-20160510042814

They're likely meant to parallel each other since they complete the phrase Rinnetensei and each belonged to one of the brothers. Only difference is one requires the chakra of two specific people to be combined and the other apparently just needs any pure Hyūga and Ōtsutsuki. And also the Tenseigan isn't permanent, apparently.