Alpha: The alpha of the pack is the leader. He is the main one in control and sets the laws of his pack. They are not required to hunt with the pack, but most normally do. They demand respect and are in the position to exile, banish, or even kill those who do not show it. Though it is rare, this position can be challenged and if the challenger wins the fight than the challenger, being the new alpha, can do what he/she pleases with the previous leaders. This does not normally happen because it would result in a huge change within the pack.
Beta: The Beta is the second in command and enforces the law when the current alpha is not present. If both of the alpha die than the beta(s) take the alpha position and lead the pack, unless the alpha has said otherwise. This position cannot be challenged without the alpha approval.
Delta: There are two deltas, they are handpicked by the Alpha and Beta and are normally younger than both of the alpha and beta by at least around three years (it doesnt matter here but they should be younger). They enforce anything that the Alpha and Beta may tell them what to do.
Omega: They are closest with the Beta and they are potential love interests for the Beta as well as the Alpha. They take care of the Pack's children mainly and if all of the positions above them aren't around for a certain occasion the Omega will be there.
Herbalist: They are the healers of the pack and have extensive experience with Herbal medicine. They are the most valuable member of the pack and need to be often protected the most.
Protector: They protect the Alpha and the Beta wherever they go and the also protect the whole pack. Due to this there are a total of five protectors because there always has to be a protector with the Alpha and Betas at least 99% of the time.
Elders: The elders of the pack are at least five years older. They are filled with wisdom and renowned strength. They are the ones that the alphas normally go to for advice. If they are wise, the elders are the only ones to whom the alphas may submit themselves to. The are respected as much as the alphas by the entire pack.
Assassin: Assassin is the most fitting name for this rank because it is self-explanatory. They are also spies for the pack. There can be a total of only four assassins in each pack.
Pups: I'm pretty sure that this is self-explanatory.