Are the names of efreets, ghouls, marids and so on, common behavior traits among jinnis or are they "racial"?

I've read that marids and efreets are considered "most powerful"* And that makes it sounds like they're different djinn-races.

But someone also told me that jinnis becomes more powerful with age... Which makes it sound like every jinni can become equally powerful!
Anybody knows?


*Whatever that means. What exactly defines a jinni's power? I though they weren't magical!?