In the US, you would need to qualify each of these. Without qualification, the hierarchy would probably be: diploma (without qualification, this would usually be understood to mean high school diploma) licence (without qualification, this would usually be understood to mean driver's licence) certificate (a certificate could be something a store gives you to indicate you're a regular customer) However, a licence can be very exclusive, like an architect's licence, which would indicate a college degree, in addition to years of experience, and the passing of rigorous professional architectural licencing exams, which is why further qualification is needed with each.
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