There are three kinds of brood comb – one for each caste of honey bee…
Worker comb – Obviously is the comb that worker bees are raised in. Most of the comb in the brood nest will be worker comb.
Drone Comb – Drone comb is noticeably larger than worker brood – and really does look like corn pops cereal. The left side of this frame (below) is capped drone brood and the right side is capped worker brood. This is not an unusually large amount of drone brood and does not indicate a failing or drone laying queen – quite the contrary, a drone brood pattern like this is typical of a healthy hive. Both kinds of brood comb will be used for honey storage when the hive needs it – and in fact there is nothing wrong with using drone comb in honey supers.
Queen Cups – Queen cups are brood comb for queens – Queen cups are very different from other brood comb in that they are much larger and that they point downwards. The natural, normal way for a colony to raise a new queen is for the workers to first build a cup and then for the queen to lay an egg in the cup which the nurse bees will raise to become a queen. However any healthy hive will build cups even when they do not plan to swarm or supercede their existing queen. Try not to panic when you find them.
In the event that a hive loses its queen (such as by beekeeper error) the nurse bees will convert an existing worker comb (with an appropriately young larva already growing in it) into a queen cell by first filling it with royal jelly to float the larva out and then they will remodel the emergency queen cell to point down like a normal one. In this kind of event they can not use a cup because they do not move eggs or larva around – ever.