Bouillon cubes do make broth.
1 bouillon cube can make one cup of broth by dissolving it in one cup of boiling water.
Bouillon cubes can also be melted directly in curries, sauces, stews and soups to enhance the flavor and also add a thicker consistency.
You can use bone broth instead of stock as both bone broth and stock are interchangeable and it's okay to substitute broth for stock in most recipes and vice versa.
However if you have a choice then you should use broth when a dish is largely based on the flavor of the liquid such as in broth based soup.
Beef stock and broth are similar but not the same.
The beef stock is made of bones and the broth is made mostly from vegetables and meat.
Also using bones in stock creates a thicker liquid while the broth tends to be thinner and also more flavorful than beef stock.
Chicken bone broth is better than the beef bone broth.
The chicken bone broth has slightly higher protein content than beef bone broth does and chicken bone broth in my opinion tastes better than the beef bone broth as well.
When using chicken bone broth make sure you add the feet to it to make it taste much better as it won't be as good without the addition of the feet to the chicken bone broth.
Beef bone broth is also good but not as tasty or good as the chicken bone broth is.
I always prefer to use the chicken bone broth over the beef bone broth.
Drinking some of the chicken bone broth is also good for a cold or even flu or when you have a sore throat.