Q. When do you use "Sumimasen" as "Thank you"? Is there any difference from "Arigatou"?
A. Though it is mostly personal preference and there is no hard rule when to use either "Sumimasen （すみません）" or "Arigatou （ありがとう）," there are a few things I can point out.
- When you asked a favor and somebody did it for you, you might use "Summasen."
In this case "Sumimasen" also has nuance of "I am sorry"
as well as "Thank you." (Basically you are saying "I am sorry
to bother you and thank you for doing this.")
- Older people tend to use "Sumimasen" more than younger people.
- When you are talking to a close friend or family members, "Arigatou" is generally used.
Click here for the difference between "Sumimasen" and "Gomennasai （ごめんなさい）."
