The Americans with Disabilities Act and Section 504

Access Board
U.S. Access Board (formerly the Architectural and Transportation Barriers Compliance Board).
U.S. Department of Justice.
U.S. Department of Transportation.
Office for Civil Rights; for example, OCR at the U.S. Department of Education.
1991 Regulations
Regulations issued by DOJ in 1991 (the original regulations) for title II and title III. They include the 1991 Standards.
1991 Standards
The ADA Standards for Accessible Design, issued by DOJ in 1991 (with some later amendments) as part of the 1991 Regulations.
2010 Regulations
Regulations published in the Federal Register on September 15, 2010, by DOJ for title II and title III. They make some changes to the 1991 Regulations and adopt new accessibility standards.
2010 Standards
Standards published in the Federal Register on September 15, 2010, by DOJ for title II and title III. The Standards include 2004 ADAAG (the ADA portions) and the other sections of the DOJ regulation that relate to new construction and alterations.
Americans with Disabilities Act Accessibility Guidelines (developed by the Access Board).The ADA says that federal ADA accessibility standards, which are issued by DOJ and DOT, must be at least as stringent as these.
“Original” ADAAG or 1991/1994 ADAAG
DOJ and DOT adopted these, word for word, as standards for the ADA.
“New” ADAAG or 2004 ADAAG
Guidelines developed by the Access Board and issued in 2004. In September 2010 DOJ adopted them as part of the 2010 Standards for title II and title III, and added other requirements as well. DOT adopted the 2004 ADAAG as new ADA Standards in 2008.
American National Standards Institute. ANSI is a private group that has developed many technical “industry standards” or “consensus standards,” including ANSI A-117.1 (accessible buildings and facilities).The 1961 ANSI Standard was the original standard under the Architectural Barriers Act and section 504.
International Building Code.This is a private “model code,” also developed by a private group, the ICC (International Code Council). A number of state and local governments have adopted the accessibility portion of the IBC, in whole or in part.
The Uniform Federal Accessibility Standards, issued in 1984, originally for purposes of new construction and alterations under the Architectural Barriers Act. Until March 15, 2012, title II entities can follow these for ADA purposes. Then they must follow the 2010 Standards.