The difference between Spontaneous and Voluntary

When used as adjectives, spontaneous means self-generated, whereas voluntary means done, given, or acting of one's own free will.

Voluntary is also noun with the meaning: a short piece of music, often having improvisation, played on a solo instrument.

Voluntary is also adverb with the meaning: voluntarily.

check bellow for the other definitions of Spontaneous and Voluntary

Spontaneous as an adjective:

Self-generated; happening without any apparent external cause.

Examples:

"He made a spontaneous offer of help."
Spontaneous as an adjective:

Done by one's own free choice, or without planning.
Spontaneous as an adjective:

Proceeding from natural feeling or native tendency without external or conscious constraint
Spontaneous as an adjective:

Arising from a momentary impulse
Spontaneous as an adjective:

Controlled and directed internally; self-active; spontaneous movement characteristic of living things
Spontaneous as an adjective:

Produced without being planted or without human labor; indigenous

Examples:

"a spontaneous growth of wood"
Spontaneous as an adjective:

Random.
Spontaneous as an adjective:

Sudden, without warning.

Voluntary as an adjective:

Done, given, or acting of one's own free will.
Voluntary as an adjective:

Done by design or intention; intentional.

Examples:

"If a man accidentally kills another by lopping a tree, it is not voluntary manslaughter."
Voluntary as an adjective:

Working or done without payment.
Voluntary as an adjective:

Endowed with the power of willing.
Voluntary as an adjective:

Of or relating to voluntarism.

Examples:

"a voluntary church, in distinction from an established or state church"

Voluntary as a noun (music):

A short piece of music, often having improvisation, played on a solo instrument.
Voluntary as a noun:

A volunteer.
Voluntary as a noun:

A supporter of voluntarism; a voluntarist.