cultural difference

Both of my parents are 100% Chinese and I was mainly grow up Chinese Culture. I came to American when i was 10 and i realized there are various cultural differences between America and Chinese. The most obvious difference is the ways that how people greet the elders. Back in China I will call my friend's parents uncle and aunt. It's rude to call their first name and last name directly. I remember once I met one of my classmate's mother in America and I call her "Aunt." She corrected mmme immeddiately and addressed me to call her Joyce or Mrs. Chou. She explaned to me that in America they only calle the sister of one's father or mother and the wife of one's uncle "Aunt."