H.V.M.N. Ketone Ester causes exogenous ketosis. Exogenous ketosis occurs when you consume ketones directly.
Ketosis is characterized by blood concentrations of ketone bodies over 0.5 mM.
Endogenous ketosis occurs when the body naturally produces ketones as a result of a ketogenic diet or fasting.
But the key, measurable endpoint of either endogenous ketosis or exogenous ketosis is the same: blood ketone levels of over 0.5 mM. There are likely to be different benefits/effects of exogenous and endogenous ketosis.