Don't confuse publicity with public relations. Publicity is a form of public relations. It's information with news value, issued through the news media as a means of gaining public attention, understanding, or support. It's a third party endorsement of you, your company or its products. It's a free delivery of your message.
If a major publication, like the Wall Street Journal for instance, says you are a good company, it's much better than you saying it yourself. Publication editors look for information that will interest their readers.
Not all public relations from your company is interesting to readers, so make sure your publicity is. Think of who will be reading your publicity and write it so it's both truthful and interesting to the readership.