Actually you can just do all of em-, but he grand assault is made up with a LEADERBOARD- (the same goes with Total Assault)
those levels are insane as f**k (unfit with a chibi game-)
-Normal (begins with nearly 1 million health bar)
-Hard
-Very Hard (the level that i currently can beat)
-Hardcore
-Extreme
-Insane (people usually stop at this level)
-Torment (boss's health bar goes up to 300 million, along with unbreakable defense)
-and LUNATIC (only actually insane people play this)
There're like ratings and you can get trophies to decorate in your cafe :3