Nailbomb is phatter, hotter, and definitely really angry. It's a raw, tempermental, and really pissed off pickup.
The Juggernaut is way fatter, hotter, and aggressive, but it is more consonant and 'polite' sounding than the Nailbomb.
To compare, the Juggernaut is a tattooed bodybuilder (Lee Priest) in a tux. The Nailbomb is a scenester with lots of metal in his face, crazy hair, tattoos all over, and crazy clothes! The Nailbomb is a fantastic pickup with lots of bite.
The Rebel Yell is a more consonant, clearer, and brighter pickup than the Nailbomb. They are similar but I was also surprised how different they are. The Rebel Yell has that same 'polite' sort of a vibe as the Juggernaut.