If you buy a certificate after taking a paid or a free test, you will be sent a high quality, mountable hard copy certificate within 3-4 weeks of successfully completing the test. You will also get logo-usage rights (for your resume, letterheads and visiting cards), a free online transcript (for 1 year) and the ability to send your result to an employer through the result-forwarding system.
If you take a free test without paying for the paper certificate, you only get the logo-usage rights and do not get a free online transcript, the ability to send the results to an employer or the paper certificate.