What are the differences in protein content between chicken broth and chicken stock?
I very quickly found nutritional information for storebought (Swanson) chicken broth and chicken stock. As you'd expect, neither one contains all that much protein. The stock does contain substantially more: 4g per cup compared to 1g - this should also be expected, since stock has some gelatin in it, and gelatin is mostly protein.

Of course, it's commercially made; I imagine you'd be hard-pressed to find good nutritional data for homemade stock and broth.