We regularly rely on our personal feelings, tastes, or opinions to arrive at conclusions.  Sometimes these can be strongly influenced by unconscious bias (i.e., things are not even fully aware of). This is a subjective approach.

In the objective approach, fact-based judgements are not influenced by personal feelings or opinions.  In this case, facts are always the same for everyone.

True objective measures provide no opportunity for interpretation.  For example, two plus two equals four is a fact.  It is accepted as always being true.

Outcomes

Actions are based on our understanding and analysis.  Often subjective information (easiest to obtain) is readily available and what we act on.

Subjective information could be accurate or inaccurate resulting in decisions that might lead to success or might not.  Of course using  objective information does not guarantee success but results are far more predictable.

Analysis

Whether objective or subjective, sometimes a combination of both types, the quality of the decision will rely on the analysis, that is the interpretation of the data gathered.

Analysis should include weighing  the quality of the inputs relative to how certain the facts are.  Objective facts will always be more certain but determining what they tell you can be tricky.

Testing

Sometimes testing the facts through trials or demos is an approach to separate subjective from objective inputs as this can be a grey area.

Walking through the recommended solution(when feasible) can help identive weaknesses in the knowledge base. This validation process canbe a very useful quality check.