Rooney was the raw, unstoppable force that made historic titles for United happen... 2011 vs City or that assist to RvP are just examples among other things he did to keep his team challenging non stop. Scorer of all kinds of goals, assist provider from every distance, I can go on, but most of all, he was one persistent c*nt who didn't want to let Fergie down, even when he had dips in form and his own issues, which he clearly had.
Kane's sometimes looks indeed a better, modern version of Le Tissier (Berba's words). Visibly better than Rooney but strictly in just few aspects, still plenty of time to grow further into greatness. His decisions off the pitch could be key in reaching something similar.
Other than that, they're just different attackers, hard to compare. Kane would probably excel much more together with Rooney in one team, as Wayne was successful previously with pletora different type of strikers in the past.