I believe that Nike is a publicly traded company, call symbol NKE, trading at about $53/share. So you can buy yourself a piece of Nike if you want, unlike say Menard's where you can save big money but not make big profits, it is not publicly traded. Nike is "private" in that it is owned by individual shareholders(including other private groups such as mutual funds), rather than being owned by the government, such as the Post Office, NASA, apparently Chrysler, maybe GM, and some big banks, at least partially.
A private company differs from a public company by how it does its research. A public company can dip into public capital markets as to where private companies cannot.
public company
Private
Mars is a private company.
Godrej is a private company.
ConocoPhillips is a Public company.
No, a private company remains private even if a public company holds a percentage of its paid-up capital. The status of a company as public or private is determined by its articles of association and the provisions of the Companies Act in the relevant jurisdiction.
private
Reliance is a private sector but public limited company.
It is a private company.
Public
Public.