Yeah, as pointed out, in general, to hit a beast, you are boosting to hits, to hurt a jack you are boosting damage.
I disagree with the idea that jacks can take more damage, they may have more boxes before becoming wrecks, but you can kill a jack with just over 3 columns of damage, barely over 50% damage, where as beasts are still up and running almost 100% until that very last point is gone. That said, the transfer system tends to mean that beasts are going to be taking some hard hits that they normally wouldn't be so hurt from (average of 3 more points of arm than casters), but that means your caster can take a hit and keep on going.
Tactics tend to be differenet between the systems because of the fury/focus issue. Leaving a caster out can mean the game, with a lock, you can still transfer if it goes horribly wrong.
Average of 14 def on troops (13 on most trolls and skorne, 14s on legion and circle) is 1 point higher than WM, but arm is roughly 1 point less. See above about boosting.
As it sits now, hordes has some decent shooting units, but not MANY of them. The catapults are nice, but expect cannons to come in for WM soon, as well as dragoons and light cav. Hordes has light cav now, and they are awesome! Plus, hordes has a fair share of weapon masters to unit ratio.
The one thing that is amusing is that hordes does have more power attack options and simply more models that can use them (ratio wise). Rends are amusing if you can set it up right. And bouncing beachball beasts is a fun game to play (throwing your own beasts when they are buffed to be "can't be knocked down", and having them kill stuff that was otherwise unreachable.
All generalities though.
Warmachine has robots, gotta say that's pretty cool, but hordes has monsters (franken thagrosh, landshark carniveans, werewolves, critters shredders, prince babar of the skorne). Pick your vice carefully.