Most accountants are certified accountants. There is not a big difference in educational background, but most accountants get certified because it is an important credential that shows your competency in accounting. In other words, accountants get certification to order to be more competitive when seeking jobs.
There are many different types of certification. The most popular is a Certified Public Accountant--there are 450,000 active CPAs in the United States, and to obtain the certification, the accountant needs to pass an exam, which is known to be quite difficult. Other types of certification include CMA (Certified Management Accountant), CIA (Certified Internal Auditor), and CGFM (Certified Government Financial Manager).