Jigen had been grooming Kawaki as a host to Isshiki Otsutsuki's power throughout Boruto: Naruto Next Generations so far, but the latest chapter of the series finally got into the why Kawaki will be a better host and what makes him different from Jigen. It was previously revealed that Jigen wasn't initially groomed to be a Otsutsuki Clan host like Kawaki, but instead was a nearby monk who happened to be taken over by a desperate and dying Isshiki Otsutsuki. It turns out that Kawaki's ninja tool enhanced body makes him even more different than Jigen than expected too.
Just like in the fight between Jigen and Naruto and Sasuke, Jigen's fight with Kashin Koji in Chapter 47 of the series brings Jigen's body to the limit as his chakra begins to break down. But with Kawaki's super body, Isshiki would be unstoppable if he revives within his body. But the real difference comes down to their Karma marks.
The Karma mark is indeed a technological program that acts as a backup file that revives an Otsutsuki into their vessel once they die, but Isshiki had two. Because Kashin Koji forcibly made Isshiki revive within Jigen, and Kawaki had yet to completely evolve in his use of Karma, Isshiki revived within Jigen and Kawaki is seemingly saved from such a fate as the Karma leaves his body following the revival.
Due to Isshiki having two vessels, a fail safe in the Karma program kicked in that keeps and Otsutsuki Clan member from reviving in two different vessels at once. For whatever reason, they don't want to copy themselves more than one at a time. This means Kawaki is presumably freed from this future possession, and now Isshiki no longer has a back up body ready. Now is the time for the Hidden Leaf Village to make its move, but there could be all kinds of unforeseen complications before its all over.
But what do you think of the differences between Kawaki and Jigen as vessels? How do you feel about Karma's new purpose in the series as a technological program rather than a mystical one? How well do you think the Otsutsuki Clan story has been carried over from Masashi Kishimoto's original Naruto series? Let us know your thoughts in the comments or you can even reach out to me directly about all things animated and other cool stuff @Valdezology on Twitter!