difference between American and British /ӕ/ sound

When I presented British /?/ sound to three Korean English-familiar persons online - they are doing answering English-related questions activities, and asked what sound it’s like /?/ or /?/, astonishingly all three of them without hesitation checked out /?/. That shows how difficult it is to differentiate the two sounds for Koreans.
I can perceive both British and American /?/ are made at the front. But the former sound is far more similar to Korean’s [?] sound. That’s why the Koreans all hear /?/. And this definitely shows, I wonder, that there’s some difference between British and American /?/. Would you let me know the difference?