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.
Example: ACE, Adobe InDesign® CS

Specialist certification:
Recognizes your proficiency in a specific medium: print, Web, or video. To become certified as a Specialist, you must pass the exams on the required products listed below.
Example: ACE Print Specialist (with passing marks on the tests for Adobe InDesign, Adobe Acrobat®, and either Adobe Photoshop® or Adobe Illustrator®)

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.
Example: ACE, Creative Suite Master (with passing marks on the tests for Adobe Acrobat, Adobe GoLive®, Adobe Illustrator, Adobe InDesign, and Adobe Photoshop)

Specialists must pass all required (R) exams and any one elective (E) within any given certification track