well,like ive metioned before, square enix games alwayse copyies off other games that they have made in the past. But they do try to keep them similar but in a different way, music and a name of somthing really shouldn't be called as a similarity, like FFx Shiva, Ifrit, Bahamut are aeons (summons) but in FF12 they are ships. But in kingdom hearts 1 and 2, there are a few characters from the FF series, (tife, aeris, cloud, squall(leon), wakka, tidus, and probly more), so like I said square enix just coppies off past games they made so when you say similarties you can go on forever, the only thing different are some monsters and characters but thats for a different reason.