Don't think Whyte's improved a lot more than that loss. Whyte's basically a weaker version of Joshua, with slightly less power in my opinion.
Whytes a better boxer now than the first fight, a bit more disciplined, his jab is improved as has his punch variety. AJ has got worse, he was better when he was a more raw punching machine. Now he seems a lot stiffer. Both chinny, AJ has more power but dill has enough to spark him. I would favour AJ but it's a shootout.
Its a good fight, I'd pick Whyte. Personally I have a feeling AJ is one of those fighters that are never the same after a defeat, that aura goes, that arrogance is gone, fighters will turn up and have a go at him because he looked really vunerable against Ruiz. With Whyte, he had to take the bitter defeat to AJ in a heated domestic clash, take the humiliation and has turned his reputation around with the British Boxing fans by showing incredible mental strength and proving it in the ring with winning performances. Whyte has proved himself a real fighter, AJ hasn't yet.
Neither can take a punch. Whoever lands flush first. Most probably AJ as he's better in every category.
Joshua comes through Ruiz then Whyte is very likely going to get the opportunity to put his chin on the line.