There are three levels of certification to become an Adobe Certified Expert.
Single product certification. Recognizes your proficiency in a single Adobe product. To qualify as an ACE, you must pass one product-specific exam.
Specialist certification. Recognizes your proficiency in multiple Adobe products with a specific medium: print, Web, or video. To become certified as a Specialist, you must pass the exams on the required products. To review the requirements, go online to http://www.adobe.com/support/certification/ace_certifyl.
Master certification. Recognizes your skills in terms of how they align with the Adobe product suites. To become certified as a Master, you must pass the exam for each of the products in the suite.