I'm pretty sure I got them all sorted out right but I'm having a little trouble figuring out how loĝantaro, etno, and popolo are different.
Raso-race, concerned with your genetics and physical features.
Gento-tribe is probably the closest word. People of different families with a common ancestor usually having their own stories about their origin and have a common ruler.
Etno-ethnicity, your traditions, beliefs, language that identify you with a group of people.
Loĝantaro-population, the whole of people who live in a certain defined area (city, state, country).
Popolo-group of people living together who are different than other groups around them. (I know popolo has other meanings to but I'm concerned with this one)
Where I live there's lots of hispanics and Latinos and I'm white, so we are part of the same population but different groups. But isn't that your ethnicity?