Both slick boxers and movers. Tunney beat Dempsey 2x, albeit a post prime Dempsey and Conn beat many of the leading HW contenders of his day and reigned as light heavyweight champion.
I think Conn uses his edge in speed to get off to an early lead, but Tunney increasingly imposes his natural size & firepower as the fight progresses & eventually wins on points.
Conn was good but he was not Greb I see Tunney rising to the occasion...the only question I have is how does Tunney OR Conn do against fast movers like themselves?
Seems like you have 3 questions, actually. Anyway, both Tunney & Conn broke into the HW ranks by stopping a very good boxer - Tunney vs. Gibbons & Conn vs. Pastor.
The exaggeration that Tunney is a mover, dancing away from opponents has reached almost mythic status. He fought Dempsey that way - he did not fight most opposition that way. He has a better punch than Conn, better chin, greater accuracy, a superior ring IQ, & at least comparable handspeed. He can press the fight, or make Conn press it. I only see one winner here & that’s the more intelligent, more versatile & harder hitting Tunney.