25 CFR §170.100

1. (a)Consultation means government-to-government communication, carried out in accordance with applicable Executive Orders, in a timely manner by all parties about a proposed or contemplated decision. The Departments' Consultation Policies and Plans can be found at http://www.indianaffairs.gov/WhoWeAre/AS-IA/Consultation/Templates/index.htm (DOI) or http://www.fhwa.dot.gov/tribal/news/consultation.htm (DOT)
2. (b)Collaboration means that all parties involved in carrying out planning and project development work together in a timely manner to achieve a common goal or objective.
3. (c)Coordination means that each party:
   1. (1)Shares and compares in a timely manner its transportation plans, programs, projects, and schedules with the related plans, programs, projects, and schedules of the other parties; and
   2. (2)Adjusts its plans, programs, projects, and schedules to optimize the efficient and consistent delivery of transportation projects and services.