1. na·tion ( P ) Pronunciation Key (nshn)
n.
A relatively large group of people organized under a single, usually independent government; a country.
The territory occupied by such a group of people: All across the nation, people are voting their representatives out.
The government of a sovereign state.
A people who share common customs, origins, history, and frequently language; a nationality: “Historically the Ukrainians are an ancient nation which has persisted and survived through terrible calamity” (Robert Conquest).
A federation or tribe, especially one composed of Native Americans.
The territory occupied by such a federation or tribe.
2. nationality
na·tion·al·i·ty ( P ) Pronunciation Key (nsh-nl-t, nsh-nl-)
n. pl. na·tion·al·i·ties
The status of belonging to a particular nation by origin, birth, or naturalization.
A people having common origins or traditions and often constituting a nation.
Existence as a politically autonomous entity; national independence.
National character.
Nationalism.
3. tribe
tribe ( P ) Pronunciation Key (trb)
n.
A unit of sociopolitical organization consisting of a number of families, clans, or other groups who share a common ancestry and culture and among whom leadership is typically neither formalized nor permanent.
A political, ethnic, or ancestral division of ancient states and cultures, especially:
Any of the three divisions of the ancient Romans, namely, the Latin, Sabine, and Etruscan.
Any of the 12 divisions of ancient Israel.
A phyle of ancient Greece.
A group of people sharing an occupation, interest, or habit: a tribe of graduate students.
Informal. A large family.
Biology. A taxonomic category placed between a subfamily and a genus or between a suborder and a family and usually containing several genera.
4.ethnic group
n : people of the same race or nationality who share a distinctive culture [syn: ethnos]
therefore the difference is that a nation has to do with a formalized government, nationality is the people within the formalized government, tribe has a do with a group of people who are related, ethinically or otherwise and has an informal government and ethnic group has more to do with the common sharing of genes and culture
i may have missed a couple specific details but there it is in a nutshell