In regards to a predictive model and privacy/ethics/etc, regardless of your objective function and explicit parameters a model can only be judged on what it actually predicts, thus it is enough to answer the prior question to be able to answer this.

This is because of the fact that machine learning models are prone to learn quite different things than the objective function intended, hence the introduction of different intent or structure of the model must be disregarded when analysing the results.

To any degree the models predict similarly, they must be regarded as similar, but perhaps in a roundabout way.