A bug fix aims to correct behaviour that was not intended. A balance change deliberately adjusts how an option performs under the rules. Both can change a strategy, but the explanation for the change is different.
What the distinction means
An interaction may disappear because it was faulty rather than because the developer decided the surrounding character should be weaker. Conversely, an explicit adjustment to damage or cost may be a deliberate attempt to change relative usefulness.
What to consider before playing
Read the developer’s wording before describing a change as a buff or nerf. Then consider the practical effect on your usual activity. The label explains intent; the changed behaviour determines whether a favourite plan still works. A useful update summary includes both without inventing motives that the notes do not establish.
The useful takeaway
A bug fix aims to correct behaviour that was not intended. Read the developer’s wording before describing a change as a buff or nerf.