방금(bang-geum, banggeum)
Indicates an action that happened just a moment ago
When to use
immediate past, just finished action, immediate reporting
The nuance
방금 is used to express an action that happened very recently from the speaker's current time, emphasizing a very short time interval.
막(mak)
Indicates an action that has just been completed or is about to start
When to use
just finished action, just starting action, imminent action
The nuance
막 is used for actions that have just finished or are about to start, covering a slightly broader time range than 방금.