To me, Tolzien has more to prove than Hundley right now. I don't doubt the guy is a hard worker and probably knows the offense better than any backup on the roster which is why they brought him back over Flynn during the off-season. That being said, he was OK at best during spot duty as a starter in 2013 and nothing about his training camp last year was anything over-whelmingly something to gush about.
Hundley is purely a developmental prospect, and even if he doesn't have a great training camp, I think at worst he ends back up on the practice squad come final cut downs.
I think the biggest question again is do the Packers carry two or three QBs on the final 53 man roster? Up until 2013 when Rodgers got knocked out for seven weeks, the team was more than content carrying two QBs.
Obviously it will come down to play in camp and preseason games, but it will be interesting to see if both Tolzien and Hundley play well enough to make it, will they still keep both of them?