public speaking vs speaking

public speaking and speaking both are nouns.

Word	Noun	Adjective	Verb	Adverb
public speaking	Yes	No	No	No
speaking	Yes	Yes	No	No

As nouns, public speaking and speaking are synonyms defined as:

public speaking and speaking: delivering an address to a public audience

Other synonyms of public speaking include oral presentation, speechmaking.

public speaking (noun)	speaking (noun)
delivering an address to a public audience	delivering an address to a public audience
	the utterance of intelligible speech

public speaking (adjective)	speaking (adjective)
	capable of or involving speech or speaking
	capable of speech