Unlike the Earth Kingdom and the Fire Nation, the Water Tribe do not have a distinctly feudal society. While there is a royal family, there is a lack of an established noble class. While people can work their way up to becoming nobles and some families are born nobles from the wealth of their ancestors or parents; this is not something they are confined to.
Royal Family
Grand Chief/Chieftain: The grand chieftain or chief of a Water Tribe is the highest ranking member of a tribe. They are usually just called chieftains or chiefs for simplicity.
Known grand chieftains: Arnook, Hakoda (was initially a minor chief but was made a grand chief over the entire Southern Water Tribe after the Hundred Year War)
Tribe Prince: The son of a Water Tribe Chieftain.
Know tribe prince: Sokka (post-Hundred Year War)
Tribe Princess: A tribe princess was the daughter of a tribe chieftain. This was different than individual villages and clans.
Known tribe princesses: Yue, Katara (post-Hundred Year War)
Other Leaders
Minor Chieftain/Chief: Minor chieftains are the leaders of local villages, clans, or towns within tribes. They are referred to as chiefs or chieftains for simplicity unless they are around grand chieftains, then they are specifically referred to as minor chieftains/chiefs. This title is typically won through an election rather than given by birth. The election is done by a council of elders. Chieftains had to prove they were useful in combat, war strategy, and experts of tradition.
Known minor chieftains: Hakoda (during the Hundred Years War)
Village Mayor (rare): A few villages and towns established mayors who were leaders in place of minor chiefs or chieftains. This title was elected and unlike chieftains mayors didn't need to prove themselves in combat or war strategies to earn their title. Mayors were purely political, ceremonial, and inspiration leaders.
Elder Council: A group of the oldest members of a village often make up an elder council who have more authority than most villagers.
Chief Priests: Chief priests are the leaders in prayer and religious ceremonies.
Main Society
Sometimes referred to as laypeople are the regular members of society.
War officers: Captains and other leaders who are below minor or grand chieftains are have more authority in society than other civilians. These titles are earned and not just given by patronage. However, people with parents who were war officers or chieftains can be promoted more easily due to favoritism.
Example: Hahn
Healers: Nurses, doctors, and those who treat the wounded are particularly valued in society. They are given a high degree of respect.
The people: Regular citizens regardless of trade are seen as equal. This includes fishermen, hunters, builders, teachers, warriors, etc. They all have a different role but the same goal, to enrich their home.