I still don't think you understand.
Within the
class Mammalia (mammals), you have lots of different
orders (eg. Carnivorans, Primates, Rodents, Bats etc.). The general consensus is that there are 19 mammal orders. Every mammal is sorted into one of these orders. Taking the Carnivora order as an example, there are then smaller groups called
families. Every carnivoran is sorted into one of the 16 carnivoran families. One of these families is the Felidae (cats).
Every cat species in the Felidae is sorted into a
genus. The genus is the first word of the latin name (ie.
Panthera for the leopard or
Varanus for monitors). A genus contains a group of (most of the time) very closely related
species. If you have two fertile animals, if they cannot breed to produce fertile offspring, they are different species (there are some exceptions, but that is the general 'rule').
All of the bolded words are forms of classification.
What you were talking about was the order Suliformes. Pelecaniformes are a different order. Waterfowl are a different order. If you want to find out more about bird orders, go here:
Bird - Wikipedia.