Public Relations aim at free coverage for the company with their personally built media relations. Be it a press releases or a News conference, the focus is always to get free media coverage for the organization. Advertising is always a paid deal. The company pays for the particular space and time required.
In Public Relations, creativity control is never in the hands of a PR Company. Presentation is always in hands of a media organization. On the other hand, the Company owns the ultimate control of what goes into that advertisement and this works in favor of brand building. The sole idea and creativity lies in the hands of an ad copywriter.