차 and 자동차
I am confused about the difference between 차 and 자동차. I know that 차 also means tea, is that the only difference? Is it the same as how you could call a couch a sofa in English.
A quick Google search: 차 is the informal / casual form of 자동차 (official word), but they carry the same meaning.
Different characters can have different meanings. It's not like how you would call a couch a sofa (synonym), but rather how, in English, "read" is spelled the same but has two different meanings (I think it's called a homonym).
Tea (茶) and Vehicle or Car (車) are using different Hanja's in Korean and they happen to share the same pronunciation and thus the same Hangul (차).
For further explanation, see https://en.wiktionary.org/wiki/%EC%B0%A8
A little more expansion on the formation of 자동차. 자 = "Self"; 동 = "Movement", also like in 운동 (rhythmic movement); and 차 = "Vehicle", also like in 기차 (train), where 기 = "Machine".