Let's say both of them in their first 10 fights, who was more powerful and brutal, let's compare the two of them as Olympic winners as well, who would win?
Joshua was fighting more tougher competition i suppose, bashing out past it ex british champs or european journeyman, some small fighters thrown in. I wouldnt know anyone of Klitchkos first 10. Thats where you experts come in. Joshua would have been more physically developed being 3-4years older at the time of their debuts.
After 10 pro fights Joshua was 25 and had been boxing for 7 years, Wlad was 21 with the same number of years. Both were star amateurs. So Joshua has a considerable maturity advantage. 10 fights into his career Joshua had already sparred with prime Wlad, young Wlad was nearly two decades prior. It's probably an advantage for Joshua as the sparring sessions didn't stop him beating old Wlad 2.5 years later. Wlad lost to Puritty at 22 in not his 10th but his 25th fight. Very different style and attributes to Joshua sure but Puritty was a journeyman. Wlad was dropped 16 times in his career in seven fights and TKO'd four times. Realistically I think you'd have to favour young Joshua over young Wlad. But it's not a forgone conclusion as Wlad had the tools to KO him, he was much more gung-ho at that point and Joshua had never been past the 3rd round in a fight.
Young Wlad much sounder technically and I think that's the difference. He's going to land big first and AJ will be in trouble
10 fights in? It could be anyone's, but I'd favor Joshua, at that formative stage of their respective careers, to reveal Wlad's fragility.