security force vs private security force

security force and private security force both are nouns.

Word	Noun	Adjective	Verb	Adverb
security force	Yes	No	No	No
private security force	Yes	No	No	No

As nouns, security force and private security force are synonyms defined as:

security force and private security force: a privately employed group hired to protect the security of a business or industry

security force (noun)	private security force (noun)
a privately employed group hired to protect the security of a business or industry	a privately employed group hired to protect the security of a business or industry