efficacy

As nouns the difference between efficacy and functionality

is that efficacy is ability to produce a desired amount of a desired effect while functionality is the ability to perform a task or function; that set of functions that something is able or equipped to perform.

As a noun efficacy

is (uncountable) ability to produce a desired amount of a desired effect.

As an adjective feasible is

that can be done in practice.

As a noun efficacy

is ability to produce a desired amount of a desired effect.

As an adjective successful is

resulting in success; assuring, or promotive of, success; accomplishing what was proposed; having the desired effect; prosperous; fortunate; happy.

As an adjective beneficial

is helpful or good to something or someone.

As a noun efficacy is

(uncountable) ability to produce a desired amount of a desired effect.

As nouns the difference between efficacy and simple

is that efficacy is (uncountable) ability to produce a desired amount of a desired effect while simple is (medicine) a preparation made from one plant, as opposed to something made from more than one plant.

As an adjective simple is

uncomplicated; taken by itself, with nothing added.

As a verb simple is

(transitive|intransitive|archaic) to gather simples, ie, medicinal herbs.

As a noun efficacy

is (uncountable) ability to produce a desired amount of a desired effect.

As an adverb effortlessly is

without effort; without difficulty or struggle.

As nouns the difference between efficacy and potent

is that efficacy is (uncountable) ability to produce a desired amount of a desired effect while potent is (tincture) a heraldic fur formed by a regular tessellation of blue and white t shapes.

As an adjective potent is

possessing strength.

As nouns the difference between efficacy and confidence

is that efficacy is (uncountable) ability to produce a desired amount of a desired effect while confidence is passive self-assurance.

As nouns the difference between usefulness and efficacy

is that usefulness is the quality of being useful, to which extent something is useful while efficacy is (uncountable) ability to produce a desired amount of a desired effect.

As nouns the difference between efficacy and success

is that efficacy is ability to produce a desired amount of a desired effect while success is something which happens as a consequence; the outcome or result.

As a proper noun Success is

a town in Arkansas.