"I already work in a bank."
Translation:제가 이미 은행에 근무해요.
They both mean the exact same thing, just 벌써 carries a little feeling of something already happend a while ago. But they can be used interchangebly without worrying about the ectra feeling.
EDIT: I've learned recently that the main difference between 이미 and 벌써 is that 벌써 contains the nuance of surprise at the fact something already took place, whereas 이미 is simply stating a fact with hardly any nuance, if any at all. Take the following text conversation for example:
A: 난 이제 퇴근해. 저녁 먹으러 좀 준비해.
B: 밥 이미 먹었는데...
A: 벌써?! 3시 밖에 안 됐는데 왜 이렇게 일찍 밥 먹었어?
B: 그냥 배고파서
A: I'm on my way home now. Get ready for dinner
B: I already ate
A: Already?! It's not even past 3pm; why did you eat this early?
B: Because I was hungry
It's difficult to explain effectively here, so I found a very useful stackexchange answer you can look at ^^
I agree with this comment because of the way the English is written. It sounds in English like the person doesn't necessarily work AT the bank but in it - I'm thinking about banks that have cafes, etc. I would use 에 to denote "I work at the bank" but it seems like "에서" makes more sense based to directly translate the English.