Most languages have titles, honorifics, and familiar names for different family members. They mostly depend on gender and relationship to the speaker. The level of formality is often related to the difference in generations. If I am speaking to an elderly aunt, for example, I may give her her title (e.g. Aunt Agatha), but will usually only ever call my cousins by their first names.
I was recently sent a link to a full list of Chinese family titles (formal and informal; in Cantonese, Mandarin, and Taiwanese), and was frankly a bit intimidated (click the picture below to see the full list).
Most Chinese people don’t address their family members by name, but rather their title (younger sister, maternal grandmother, etc). To be perfectly honest, I’m glad I don’t have many relatives in China. I’d be terrified that I’d address my paternal grandfather’s older brother’s wife by entirely the wrong name.