If the change in the score is drastic, we should change something drastically in our playing. If it is a subtle change, the difference will be subtle. The question then becomes - how do we choose to highlight these changes? This involves musical and expressive techniques - rubatos, accents, color changes, dynamics, fingering choice, etc.
Many teachers stress listening to orchestra music. Why? Composers of the world change their orchestration (sound, dynamic, mood) when the music changes it's character. They highlight the change in the music by changing the orchestration. Again, it's simple and honest. Pay attention and you'll see what I mean.
The more we can notice the way music changes in our scores, the more we can highlight those changes in our playing and be more expressive.
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