Jon has never even been dropped or hurt, let alone KO'd. He's a great striker on top of that, even if his power's nothing special. He's one of the most dynamic and creative the sport's ever seen. The grappling is massively in his favour against everybody he fights, and the threat of the TD alone has always been a problem in and of itself for strikers.
Fury by contrast has been dropped a few times, and realistically was KO'd by Wilder in the 1st fight. He was supposedly #1 or #2 HW boxer in the world, who though relies on his size to wear down opponents not used to it in the clinch. He can only punch.
Fury is stylistically the way easier fight. We all thought he still needed his nuclear option to actually pull it off as the skill was supposed to be way more in Fury's favour, but Ngannou was taking the fight where his opponent has no option but to stand in front of him and risk that. Ngannou was fighting in his own strength.
Against Jones he meanwhile needs to stop Jones from taking him out of his strength and bypassing it entirely. Fury will be standing in front of him, Jon might instead be literally on top of him.