Granted, Vader died as well, but the fact remains that even in an extremely weakened state, including the loss of one hand, Vader tanks through Sidious' most lethal lightning and then picks him up and tosses him aside like yesterday's trash.
Well, let's not forget Vader . . .
A.) focuses for multiple minutes every fiber of his being into the attack,
B.) is imbued with light side "super energy" per George Lucas and Fact Files,
C.) is being hit with lightning that is indiscriminately firing everywhere including back at Sidious himself,
D.) has armor specifically insulated to handle Starkiller's Force lightning and extreme heat.
The fact Vader still dies despite all these factors is consistent with his equal - ROTJ Luke - being nigh-instantly downed by Sidious.
Not that "full force" can mean "full impact" just as easily as "full power" regardless, though.