yeah it's different, I know that you can't eat the processed sliced stuff, but I also thought that chopped up, actual chicken breast stored cold was a risk as well? Like what you might use from a left over roast? I think it's the fact that it's been cooked and then chilled and eaten cold?
Here is what it say's in a pamphlet I have from the hospital about Listeria.
High Risk Food:
> deli meats which are eaten with or without further cooking or heating, such as pate, ham, strass and salami, and cooked diced chicken (as used in sandwich shops).