Board Thread:General Discussion/@comment-4957813-20131130185522/@comment-9468724-20140823203746

Zangetsu is a meele type Zanpakutō. Engetsu is likely a fire-type. The two zanpakutō have different names, assumedly different shikai commands (how would "Burn" even work with Zangetsu?) and starting from the fact names are different, the zanpakutō are different. Furthermore Aizen may have commented on Ichigo's Bankai if it was similar to Ishin's .. Maybe... Either way, their similarity cannot be denied.. Maybe the father/son thing is some factor? They are legitimately blood related (unlike Byakuya and Rukia for example).