private security force vs security force

private security force and security force both are nouns.

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

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

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

private security force (noun)	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