What Bracha are the Croutons that are really just dried pieces of bread separately and when there in my instant soup and is there a difference?
The way it works:
Bread that is cut into pieces retains its status of bread (i.e. Hamotzi) no matter how small the pieces get. So if you or anyone would cut the bread and then bake it again, it wouldn't matter and it would still be Hamotzi [unless you cut it less than a K'zayis an cook it in water to a certain degree... but not so practical]
However, there's a famous shitah (R' Shlomo Zalman Auerbach) that holds that if companies make croutons - even though it's bread at an intermediate stage - since the end product will be croutons (which should be Mezonos for its own reasons) the entire product is Mezonos. In other words, it doesn't get a status of bread if the end-game is to make it into something else.
So in short:
I'm not sure about the one's in instant soup (I've never personally come across them), but is seems they're like the second type mentioned above.
I heard in the name of the Rav Ovadia Yosef that it is Mezonot, if each piece is at least Kazayit you say Hamotzi.
Look at Hazon Ovadia page סה and סו, I think it would apply to our case, maybe I'm wrong, someone please correct me.
Real croutons such that you would make yourself or have in a restaurant would be hamotzi. It's just regular bread that was cut into pieces (Shulchan Aruch O.C 165:10.
Osem makes a number of crouton varieties. These would be mezonos (S.A. O.C. 165:7, 3rd Yesh mefarshim + M.B 35)