As nouns the difference between efficacy and potency
is that efficacy is ability to produce a desired amount of a desired effect while potency is strength.
efficacy
English
Noun
(-)
(uncountable) Ability to produce a desired amount of a desired effect.
Synonyms
* efficacity
Related terms
* effect
* effective
* effectiveness
* effectivity
* effector
* effectual
* effectuate
* efficacious
* efficacity
* efficiency
* efficient
External links
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potency
English
Noun
(potencies)
Strength
Power
The ability or capacity to perform something.
Related terms
* potence
* potent
* potentate
* potential
* potentiality