How does Katniss stack up as a tribute in relation to the Careers? In what ways is she better than they are?

Unlike Careers who have trained all their lives to be tributes on a voluntary basis, Katniss offers herself as a tribute to save the life of her younger sister.

Explanation:

The comparison we can make between Katniss and the Careers is that the Careers are healthy, well fed and well trained and that is why they volunteer, while Katniss is only offered as a tribute because she could not allow her little sister to enter The Hunger Games.

Recall also that Katniss comes from a hungry district while Careers come from very well positioned districts where nothing is missing.

Regarding the ways in which Katniss is better than them, we can say first that Katniss is more sensitive and compassionate. The Careers are mostly bad people who only care about killing, while Katniss wants to fight the system.

On the other hand Katniss is also smarter while Careers only use brute and physical force. Let's also remember that Katniss is an excellent shooter with her bow and arrows.