Chalk and cheese.
The A-Bomb is incredibly tight for an alnico pickup, being tighter than many ceramics I've played. It's also very aggressive sounding and the word 'hairy' is often used to describe its tone. I found it to have a very 90s Metal feel to it that I could never quite shake. It's quite an open sounding pickup, which gives it some versatility as it will do Classic Rock very well if you want it with a very aggressive, hairy edge to it. When I had mine it was in a maple neck-thru with alder wings and a Floyd trem and in that guitar it was awful. I always felt it needed a darker, warmer guitar to to tame the aggressive hairiness a bit, which is why I'll be trying another one in the New Year in a Les Paul copy. Others disagree on that point but my experience would incline me not to use it in an alder/maple guitar.
The Holydiver is very different. It's tight and aggressive but in a far more restrained way than the A-Bomb, which to me, is why it works well in a bigger range of guitars and for more styles. It's also very smooth in its tone and has a fantastic lead tone; arguably the best of any of the contemporary bridge pickups. Think Doug Aldrich and Jake E. Lee and you're on the right lines. It's also a pickup that loves an overdrive pedal, which helps you to run from Classic Rock to modern Metal with relative ease.
