At 149% difficulty trying to take over the map the old-fashioned way, there's really no comparison. The bow is the most deadly weapon in the game.
Right now I'm at about level 25 with level 9 power draw, a hand-crafted bow, and three large bags of forged arrows. Anybody will go down with one headshot and lower tier enemies take one shot anywhere.
The bow has the potential to do more damage than any gun in the game. With +14% damage per power draw level, headshots easily exceed 250 damage. The bow is also extremely accurate with high proficiency and skills. If you can see them, you can kill them. On top of that, it's incredibly fast.
When I defend castles I just bring my bow and three bags of arrows. Nearly every arrow is a kill and I average around two kills every three seconds. Without the bow, I find it hard to see how somebody could manage to defend a castle at maximum difficulty with a 1:2 enemy ratio coming at you.
Guns can't even come close to comparing. They're far too inaccurate to be relied upon. Trajectories are very random and accuracy can't be improved by much by the proficiency. You can't get "good" at using firearms. You just get lucky from time to time. The damage is also very weak. Because you can't rely on the accuracy of the weapon, headshots are essentially random and thus most high tier enemies won't die in one shot. On top of that, the reload time is intolerable. In the time it takes to shoot and (maybe) kill two enemies with a double barreled pistol, I could have killed a good 12-20 enemies with the bow.
That's not to say that guns are useless. I think they're a great addition. They make the game much harder (especially in the beginning) and work great in clusters.