Tribals are much more dangerous than opponents in the Capital Wasteland because they do far more damage to the player due to an object effect in the DLC causing the aforementioned weapons, when wielded by tribals or swampfolk, to do an additional 35 points of unresistible damage per hit.
Tribals are surprisingly tough opponents; even the weakest of them are on par with a Brotherhood of Steel paladin in terms of durability and combat skill, and the highest-level tribals exceed even super mutant brutes and super mutant masters. Their tribal garb serves as mediocre, but still functional armor.
In contrast, named tribals, including their leader Jackson, are standard human non-player characters, and are relatively easily killed.
The named tribals may sometimes attack after Calvert is killed.