juggernaut equal bruiser

Nobody realises that, because you're wrong. All juggernauts are bruisers, but not all bruisers are juggernauts. Juggernauts are a type of bruiser in the same way that burst mages are a type of mage. You're not going to call Irelia a juggernaut just because she and Darius are both bruisers, just as you're not going to call Lulu a burst mage just because she and Syndra are both mages.

bruiser is simply a build meanisn a decent amount of defense and offense is what bruiser means liek when i build modified blue build ez. i get triforce instead of ice born and i get frozen heart for mana cd and the armor is nice

Isn't Bruiser just another word for Fighter since Bruiser is basically a Tank that deals damage, but usually has less crowd control. Juggernaut is more a reword of Raid Boss since Raid Boss champions are usually immobile enough to where they gain above average power from their skills due to them not providing mobility so a single champion usually cant defeat them.