What is daily life like in Korea?

Hi everyone, I have a question. What are the differences between daily life in Seoul and Vietnam? I've read a lot about convenience stores (편의점), convenience stores (다이소), and apps like "baedala," but I can't quite picture them. For transportation, you use T-money (교통카드), right? I've never been to Korea before, so I'm a little worried about shopping and eating out.