What's the difference between Variability risk and Ambiguity risk?

I am not an aspirant but I dare to answer. It is enough to open a dictionary.
Variability - lack of consistency or fixed pattern
Ambiguity- the quality of being open to more than one interpretation
Neither are part of standard risk assessment because you can't predict their likelihood. It a tricky question if it is intended to aspirants.
First of all it is not really aligned with risk management because risk is defined as the efect of unknown on project objectives, second neither attribute is really relevant in a project and third because understanding how variability of a process can be measured and ambiguity resolved require a level of knowledge that even experienced project managers may not have.
Variability is the object of Lean Six Sigma and require a solid theoretical foundation with deep knowledge of statistical control.
Ambiguity should be addressed by Business Analysts and/or architects, not by the Project Managers.
I will be curios to hear the 'corect' answer because although I consider myself a subject matter expert in both Lean Six Sigma and in Risk Management I will find very difficult to explain the difference to a PMP aspirant. One because of the knowledge and experience required to master the two asects in a project and second because they are not relevant for the PMP exam.

Hi Stelian - thanks for your response...

In regards to your doubt, I suggest you do a search on new topics of PMBOK version 6... you'll find the answer there...

Have a great day and again, thanks for your response.

Variability risks are due to the uncertainty of outcomes in elements of the plan. They usually result in a distribution of possible outcomes. For example, a known event may take longer than planned or cost more than expected. A risk management plan might use analysis such as Monte Carlo simulation to determine a possible range of outputs.

Ambiguity risks are due to a knowledge gap. For example, we don't know whether the regulatory agency will approve the plan. A risk management plan might postulate different potential scenarios that would disrupt the plan and how they might be handled.

It's a bit like understanding the difference between an integer, and a rational number. Trivial to some, critical to others.