"Henkei! Henkei! Transformers is the name of the Japanese version of the Classics toyline." According to the wiki, but what does Henkei mean?

Also, is there any reason given in the TF film fiction to account for the vastly different style between the mainline movie figs and the Energon/Cybertron redecoes? I'd like to see some explanation to account for the radical difference between the two